Notes

A sibling is one of two or more individuals having one or both parents in common. A female sibling is a sister and a male sibling is a brother. In most societies throughout the world, siblings often grow up together, thereby facilitating the development of strong emotional bonds. The emotional bond between siblings is often complicated and is influenced by factors such as parental treatment, birth order, personality, and personal experiences outside the family.
However, there are cases where siblings grow up in separate homes, in different environments. It is known that both nature and nurture figure in development; researchers are attempting to ascertain just which one plays the larger role.
Identical twins share 100% of their DNA. Half-siblings are second-degree relatives and have, on average, a 25% overlap in their human genetic variation.
Knowing from past studies that genetics played a larger role in one's personality during the earlier years, researchers were interested in older subjects, as to whether their theory still held. They gathered subjects with a mean age of 59, including 99 pairs of identical twins and 229 pairs of fraternal twins who were all reared separately; and 160 pairs of identical twins and 229 pairs of fraternal twins who were all reared separately. They studied the most inheritable personality traits: emotionality, activity level, and sociability . The study found that identical twins resembled each other twice as much as fraternal twins, due to genetic factors. Furthermore, environment influences personality substantially, but it has little to do with whether twins are raised together or apart. It also suggests that inheritability is substantial but has less significance later on in life.
Half-sibling
Half-siblings share only one parent instead of two as full siblings do and are on average 25% related, in other words, the children that the parent and stepparent have together. Theoretically, there is a chance that they might not be related at all though this is very rare and is due to there being a smaller possibility of inheriting the same chromosomes from the shared parent. but still exists in the U.S. State of Florida.
3/4 sibling
Three-quarter siblings have one common parent, while their unshared parents have a mean consanguinity of 50%. This includes full siblings and parent/child. . Three-quarter siblings share more genes than half siblings, but fewer than full siblings.
Horizontal
In this case the unshared parents are full siblings. Furthermore, the three-quarter siblings are also first cousins. An example of this is that of Charles Lindbergh's children with his mistress Brigitte Hesshaimer, and his children with her sister, Marietta Hesshaimer. A more recent example relates to Jermaine and Randy Jackson, of the Jackson 5, who have both fathered children with Alejandra Genevieve Oaziaza.
In the case where the unshared parents are identical twins, the children share as much genetic material as full siblings do.
See also Deceased Wife's Sister's Marriage Act 1907.
Vertical
In this case a woman has children with two men who are father and son, or a man has children with two women who are mother and daughter. These children will be three-quarter siblings.
Stepsibling
"Stepsiblings" are the children of one's stepparent from a previous relationship. They are unrelated by blood.
Godsibling
Godsiblings are the children of one's godparent. They are unrelated by blood.
Foster siblings
"Foster siblings" are children who are raised in the same foster home, foster children of the person's parents, or foster parents' biological children.
Adoptive siblings
"Adoptive siblings" are two or more children who are legally related, but not blood-related or biologically related—but they may consider each other/one another siblings because they act like they are.
Adoptive siblings that are adopted by both legal parents are considered full adoptive siblings.
Adoptive siblings that are adopted by only the same legal mother are maternal adoptive half siblings.
Adoptive siblings that are adopted by only the same legal father are paternal adoptive half siblings.
Many stigmas are attached to adoption. It is seen as a last choice because of infertility—not something fertile couples would choose to do. Some believe that mothers who give up their children for adoption have psychological or behavioral disorders that might show up in their children. But the stigma has lessened over the years, increasing the number of adoptions; despite this, the rate has dropped. Adoption policies are stricter now than ever before. Also, reproductive technology has improved substantially, offering couples more options than adoption.
Adoptive study
Research was done to see what factors affected IQ, specifically family environment and genetics. Segal was interested in siblings of no biological relations. He found that intellect and behaviour is associated with rearing situations. Rearing situation refers to being raised apart, in opposite environments; so that could be high vs. low socioeconomic status. Unrelated siblings that are reared together from infancy showed results that resemble those of dizygotic twins. This could be because, despite genetic differences and different personalities and behaviours, they are still raised in the same environment. The study suggests that IQ and rearing status did, in fact, have a significant relationship. That is to say that biological siblings had higher mean scores as compared to unrelated siblings. Age was also a factor that affected the siblings resemblance in IQ. At about age 3, they become dissimilar as they begin to follow their genetic growth curve. Their family environment having less and less of an effect as they grow. However, it does affect spatial and perceptual factors.
Sibling cousins
"Sibling cousins" are those who share a father and their mothers are sisters or cousins or vice versa. This category is broader than, but inclusive of, the horizontal 3/4 sibling above.
Sibling-in-law

Birth order
Birth order is a person's rank by age among his or her siblings. Typically, researchers classify siblings as "eldest", "middle child", and "youngest" or simply distinguish between "firstborn" and "later-born" children.
Birth order is commonly believed in pop psychology and popular culture to have a profound and lasting effect on psychological development and personality. For example, firstborns are seen as conservative and high achieving, middle children as natural mediators, and youngest children as charming and outgoing. Despite its lasting presence in the public domain, studies have failed to consistently produce clear, valid, and compelling findings. Therefore, it has honed the title of a pseudo-psychology amongst the scientific psychological community.
History
The theorizing and study of birth order can be traced back to Francis Galton's theory of birth order and eminence and Alfred Adler's theory of birth order and personality characteristics.
Galton
In his book English Men of Science: Their Nature and Nurture, Galton noted that Nobel Prize winners, classical music composers, and prominent psychologists are over-represented as first-borns. He theorized three main reasons as to why first-borns are generally more eminent:
# Primogeniture laws: first-borns have access to their parents' financial resources to continue their education.
Middle Children: Feel like outcasts of families as they lack primacy of the first child and the "attention garnering recency" of the youngest. These children often go to great lengths to de-identify themselves with their siblings, in an attempt to make a different and individualized identity for themselves as they feel like they were "squeezed out" of their families.
Contemporary findings
Today, the flaws and inconsistencies in birth order research eliminate its validity. It is very difficult to control solely for factors related to birth order, and therefore most studies produce ambiguous results.
The social interaction that occurs as a result of birth order however is the most notable. Older siblings often become role models of behaviour, and younger siblings become learners and supervisees. Older siblings are at a developmental advantage both cognitively and socially. The role of birth order also depends greatly and varies greatly on family context. Family size, sibling identification, age gaping, modeling, parenting techniques, gender, class, race, and temperament are all confounding variables that can influence behaviour and therefore perceived behaviour of specific birth categories. The research on birth order does have stronger correlations, however, in areas such as intelligence and physical features, but are likely caused by other factors other than the actual position of birth. Some research has found that firstborn children have slightly higher IQs on average than later born children. However, other research finds no such effect. It has been found that first-borns score three points higher compared to second borns and that children born earlier in a family are on average, taller and weigh more than those born later.
Literature reviews that have examined many studies and attempted to control for confounding variables tend to find minimal effects for birth order on personality.
In her review of the scientific literature, Judith Rich Harris suggests that birth order effects may exist within the context of the family of origin, but that they are not enduring aspects of personality.
In practice, systematic birth order research is a challenge because it is difficult to control for all of the variables that are statistically related to birth order. For example, large families are generally lower in socioeconomic status than small families, so third-born children are more likely than first-born children to come from poorer families. Spacing of children, parenting style, and gender are additional variables to consider.
Regressive behavior at the birth of a new sibling
The arrival of a new baby is especially stressful for firstborns and for siblings between 3 and 5 years old. Regressive behavior and aggressive behavior, such as handling the baby roughly, can also occur. All of these symptoms are considered to be typical and developmentally appropriate for children between the ages of 3–5. While some can be prevented, the remainder can be improved within a few months. Regressive behavior may include demand for a bottle, thumb sucking, requests to wear diapers, or requests to carry a security blanket.
Regressive behaviors are the child's way of demanding the parents' love and attention.
The American Academy of Pediatrics suggests that instead of protesting or telling children to act their age, parents should simply grant their requests without becoming upset. The affected children will soon return to their normal routine when they realize that they now have just as important a place in the family as the new sibling. Most of the behaviors can be improved within a few months.
The University of Michigan Health System advises that most occurrences of regressive behavior are mild and to be expected; however, it recommends parents to contact a pediatrician or child psychologist if the older child tries to hurt the baby, if regressive behavior does not improve within 2 or 3 months, or if the parents have other questions or concerns.
Sibling rivalry
"Sibling rivalry" is a type of competition or animosity among brothers and sisters. It appears to be particularly intense when children are very close in age or of the same gender. Sibling rivalry can involve aggression; however, it is not the same as sibling abuse where one child victimizes another.
Sibling rivalry usually starts right after, or before, the arrival of the second child. While siblings will still love each other, it is not uncommon for them to bicker and be malicious to each other. Children are sensitive from the age of 1 year to differences in parental treatment and by 3 years they have a sophisticated grasp of family rules and can evaluate themselves in relation to their siblings. One study found that the age group 10–15 reported the highest level of competition between siblings. Sibling rivalry can continue into adulthood and sibling relationships can change dramatically over the years. Approximately one-third of adults describe their relationship with siblings as rivalrous or distant. However, rivalry often lessens over time and at least 80% of siblings over age 60 enjoy close ties. Evolutionary psychologists explain sibling rivalry in terms of parental investment and kin selection: a parent is inclined to spread resources equally among all children in the family, but a child wants most of the resources for him or herself. Jealousy occurs in a social triangle of relationships which do not require a third person. The social triangle involves the relationships between the jealous individual and the parent, the relationship between the parent and the rival, and the relationship between jealous individual and the rival. These implicit beliefs determine both the intensity of their jealous feelings, and how long those jealous feelings last. The first category is conflict about equality or fairness. It is not uncommon to see siblings who think that their sibling is favored by their teachers, peers, or especially their parents. In fact it is not uncommon to see siblings who both think that their parents favor the other sibling. Perceived inequalities in the division of resources such as who got a larger dessert also fall into this category of conflict. This form of conflict seems to be more prevalent in the younger sibling.
The second category of conflict involves an invasion of a child’s perceived personal domain by their sibling. An example of this type of conflict is when a child enters their sibling’s room when they are not welcome, or when a child crosses over into their sibling’s side of the car in a long road trip. These types of fights seem to be more important to older siblings due to their larger desire for independence.
Sibling warmth
Sibling warmth is a term for the degree of affection and companionship shared by siblings. Sibling warmth seems to have an effect on siblings. Higher sibling warmth is related to better social skill and higher perceived social competence. Even in cases where there is a high level of sibling conflict if there is also a high level of sibling warmth then social skills and competence remains unaffected. Sibling warmth, however, is correlated to some more negative effects in pairs of brothers. In pairs of brothers higher sibling warmth is related to more risk taking behaviour although risk taking behaviour is not related to sibling warmth in any other type of sibling pair. The cause of this phenomenon in which sibling warmth is only correlated with risk taking behaviours in brother pairs still is unclear. This finding does, however, suggest that although sibling conflict is a risk factor for risk taking behaviour, sibling warmth does not serve as a protective factor.
Negative effects of sibling conflict
The saying that people "fight like siblings" shows just how charged sibling conflict can be and how well recognized sibling squabbles are. In spite of how widely acknowledged these squabbles can be, sibling conflict can have several impacts on the sibling pair. It has been shown that increased levels of sibling conflict are related to higher levels of anxiety and depression in siblings, along with lower levels of self-worth and lower levels of academic competence. In addition, sibling warmth is not a protective factor for the negative effects of anxiety, depression, lack of self-worth and lower levels of academic competence. This means that sibling worth does not counteract these negative effects. Sibling conflict is also linked to an increase in more risky behavior including: smoking cigarettes, skipping days of school, contact with the police, and other behaviors in Caucasian sibling pairs with the exception of firstborns with younger brothers. Except for the elder brother in this pair sibling conflict is positively correlated with risky behavior, thus sibling conflict may be a risk factor for behavioral problems.
A study on what the topic of the fight was also shows that the topic of the fight may have a result on the effects of the conflict. This study showed that sibling conflict over personal domain were related to lower levels of self-esteem, and sibling conflict over perceived inequalities seem to be more related to depressive symptoms. However, the study also showed that greater depressive and anxious symptoms were also related to more frequent sibling conflict and more intense sibling conflict.
Parental management techniques of sibling conflict
There are several different techniques used by parents to manage their children’s conflicts. These techniques include parental non-intervention, child-centered parental intervention strategies, and more rarely the encouragement of physical conflict between siblings. Parental non-intervention included techniques in which the parent ignores the siblings conflict and lets them work it out between themselves without outside guidance. In some cases this technique is chosen to avoid situations in which the parent decides which sibling is in the right and may favor one sibling over the other, however, by following this technique the parent may sacrifice the opportunity to instruct their children on how to deal with conflict. Child-centered parental interventions include techniques in which the parent mediates the argument between the two children and helps them come to an agreement. In this technique parents may help model how the children can deal with conflicts in the future; however, parents should avoid dictating the outcome to the children, and make sure that they are mediating the argument making suggestions thus do not decide the outcome. Techniques in which parents encourage physical aggression between siblings may be chosen by the parents to help children deal with aggression in the future, however, this technique does not appear to be effective as it is linked to greater conflict levels between children. Parental non-intervention is also linked to higher levels of sibling conflict, and lower levels of sibling warmth. It appears that child-centered parental interventions have the best effect on sibling’s relationship with a link to greater levels of sibling warmth and lower levels of sibling conflict.
Long-term effects of sibling presence
Previous studies done on whether there are any social skills or personality differences between children with siblings or only children seem to suggest that overall the presence of a sibling does not seem to have any long-term effect on the child by the time the child reaches adulthood. This study, however, failed to take into account the type of relationship that the siblings had and as such it is still unclear if siblings and their different forms of relationships have long-term effects.
The book Nicomachean Ethics, Book VIII written by Aristotle in ¬350 B.C.E., offers a way in which people should view the relationships with their families. The relationship of brothers is laid out with the following quote:
"The friendship of brothers has the characteristics found in that of comrades and in general between people who are like each other, is as much as they belong more to each other and start with a lover for each other form their very birth, and in as much as those born to the same parents and brought up together and similarly educated are more akin in character; and the test of time has been applied most fully and convincingly in their case"
For these reasons, it is the job of the older brother to influence the ethics of the younger brother by being a person of good action. Aristotle says "by imitating and reenacting the acts of good people, a child becomes habituated to good action". Over time the younger brother will develop the good actions of the older brother as well and be like him. Aristotle also adds this on the matter of retaining the action of doing good once imitated: "Once the habits of ethics or immorality become entrenched, they are difficult to break." The good habits that are created by the influence of the older brother become habit in the life of the younger brother and turn out to be seemingly permanent. It is the role of the older brother to be a positive influence on the development of the younger brother's upbringing when it comes to the education of ethics and good actions. When positive characteristics are properly displayed to the younger brother by the older brother, these habits and characteristics are imitated and foster an influential understanding of good ethics and positive actions.
Gender roles in siblings
There has not been an extreme amount of studies done on gender role differentiation between siblings; however there are very interesting concepts to observe in the studies that have been conducted. For one, how do parents help shape gender oriented tasks and how does it affect children in the future? Another interesting thing to observe is the relationship mothers have towards their young infants.
Gender role among children and parents
There has always been some type of differences between siblings, especially different sex siblings. Often, different sex sibling may consider things to be unfair because his/her brother/sister is allowed to do certain things just because of his or her gender, while he or she gets to do something less amusing or just plain different. McHale and her colleague conducted a longitudinal study using middle age children and observed the way in which the parents contributed to stereotypical attitudes in their kids. In their study the experimenters analysed two different types of families, one with the same sex siblings, and the other with different sex siblings, as well as the children’s birth order. The experiment was conducted over phone interviews, in where the experimenters would ask the children about the activities they performed throughout their day outside of school. Surprisingly, the experimenters found that in the homes where there were mixed gender kids, and the father held traditional values, the kids also held traditional values and therefore also played gender based roles in the home. In contrast in homes where the father did not hold traditional values the house chores were divided more equally among his kids. However,if fathers had two male children, the younger male tended to help more with household chore, but as he reached his teenage years the younger child stopped being as helpful around the house. There are two important factors that need to be taken into account from this study. First, in cases where the father figure had more traditional values it was found that he also had less education than the other dads who participated in the study, and secondly the mother’s attitudes did not have a noticeable impact on her children’s gender role values. Altogether this experiment is a good example of the way in which environment and kinship help develop certain perspectives on gender role association in children.
In a similar study, Croft and her colleagues observed the mother and father gender roles and examined whether their attitudes would have a long-term effect in the future occupation of their children. In this study mothers and fathers were asked a series of questions regarding their work hours and their chores at home, including who looked more after the children? The study demonstrated that mothers felt like they were performing more household duties and they tended to look more after the children. Something that is quite remarkable in this experiment is the way in which the kids perceive their parents gender roles. When the kids were asked which parent they would be like when they grew up, some kids did not associate themselves with either male or female occupations, but rather remained neutral, while other leaned on being more like their same gender parent, but this, just like in the study conducted by McHale and her colleagues, depended on the father’s traditional values. It was also found that girls who observed their parents playing out a gender type role envisioned themselves playing a role similar to their mothers', while daughters who lived in a home where parents did not have sex oriented tasks viewed themselves as a working women and family oriented females in the future. Altogether Croft and her team agreed that in order to create more equality, regarding work occupation the house work also needs to be divided equally.
Mother interaction between different gender children
Mothers tend to spend a significant amount of time with their kids, especially throughout their children's first years of life. An experiment conducted by Goshen-Gottstein studied how Israeli mothers socialized with same-age siblings from newborns to three years of age. Goshen paid attention to the differences mothers had regarding aggression and encouragement between their sons and daughters. In her research Goshen observed thing such as:
"Proximity Seeking:" It was found that both sons and daughters seek their mothers equally, but boys tend to be more encouraged to do so.
"Aggressive Behavior:" It was discovered that boys exhibit more "aggressive behavior" towards their elders than girls. The mothers however did not demonstrate any differences in their reinforcements, between their sons and daughters.
"Helping:"The experimenter noticed that when mothers needed help they would often ask for help from their daughters.
"Mother’s Gender Linked Talk:" It turned out that mother’s showed a similar amount of "gender linked talk" to all their children, but they emphasizes more "gender linked labels" for the children who were in the sex minority in their family. Goshen suggest that whenever the mother emphasized on "gender linked labels" it was because the mother was seeing that her child had different qualities than his or her siblings. An example of this would be referring to a girl as a ballerina and a boy as a Police officer.
Altogether, children were treated almost equally until their third year of life when mothers began dressing them according to their gender. From this experiment it is evident that mothers do not show much differentiation between different sex siblings at a young age. However, as they begin to grow the mother begins regarding her children differently based on their gender.
Westermarck effect and its opposite
Anthropologist Edvard Westermarck found that children who are brought up together as siblings are desensitized to form sexual attraction to one another later in life. This is known as the Westermarck Effect. It can be seen in biological and adoptive families, but also in other situations where children are brought up in close contact, such as the Israeli kibbutz system and the Chinese Shim-pua marriage.
The opposite phenomenon, when relatives do fall in love, is known as genetic sexual attraction. This can occur between siblings brought up apart from each other, for example, adoptees who are re-united in adulthood.
Famous sibling groups
Hans and Sophie Scholl, German students and anti-Nazi activists executed in 1943
The Koch brothers
Naturalist Alexander Humboldt and philosopher Wilhelm von Humboldt
The Marx Brothers comedians actors
The Grimm Brothers, folklorists and anthropologists
Otto and Gregor Strasser, leaders of a dissident brand of Naziism
Intellectuals Julian, Aldous and their stepbrother Andrew Huxley of the Huxley family
Cherie Currie, Marie Currie, and Sondra Currie,
The Kardashians, reality television stars and American socialites: Kourtney, Kim, Khloé, and Rob
The children of Olympian Caitlyn Jenner, reality television stars and half siblings of the Kardashians: Kendall, Kylie, Burt, Casey, Brandon, and Brody Jenner .
The Wayans Brothers, directors, screenwriters and actors
The Olsen twins: Mary-Kate and Ashley
The Smothers Brothers, comedians: Tom and Dick
The Wright Brothers, aviation pioneers and inventors: Orville and Wilbur
The Dionne quintuplets
Isabelle and Paul Duchesnay, world champion figure skaters.
Sprouse brothers, American actors: Dylan and Cole
Sutter brothers, Canadian family who played or have been associated with the National Hockey League.
Steve and Mark Waugh, Australian cricketers.
Marc and Pau Gasol, basketball players
Duncan II, Edgar, Alexander I, and David I, kings of Scotland
The Black Douglases, clashed with King James II of Scotland: William, James, Archibald, Hugh, and John
The actresses Olivia de Havilland and Joan Fontaine
The Chapman brothers, Duane Lee Chapman, II and Leland Chapman, stars of Dog The Bounty Hunter
Grand Duchess Olga Nikolaevna of Russia, Grand Duchess Tatiana Nikolaevna of Russia, Grand Duchess Maria Nikolaevna of Russia, Grand Duchess Anastasia Nikolaevna of Russia and Alexei Nikolaevich, Tsarevich of Russia . The five siblings were executed during the Russian Revolution.
Mary I of England, Elizabeth I of England, Edward VI of England
Anne Frank and Margot Frank
Karla Homolka and Tammy Homolka
Musicians
Cherie & Marie Currie American rock band, Cherie Currie and Marie Currie rock singers and songwriters
Thirty Seconds to Mars, an American rock band, Jared and Shannon Leto
A, an English rock band, Jason Perry and Adam Perry, and Giles Perry
Nelson, an American Rock Band, Matthew Nelson and Gunnar Nelson
AC/DC, an Australian rock band, Malcolm and Angus Young
Ace of Base, a Swedish quartet consisting of the three Berggren siblings and family friend Ulf Ekberg
The Allman Brothers Band, an American southern jam band led by Gregg Allman and the late Duane Allman.
Anathema, an English band, formerly death-doom metal, later alternative rock, Daniel, Vincent, and Jamie Cavanagh; John and Lee Douglas
The Andrews Sisters, an American close-harmony singing group, LaVerne Sophia, Maxene Angelyn, and Patricia "Patty" Marie Andrews
Architects, British rock band, Dan and Tom Searle
Arch Enemy, a Swedish melodic death-metal band, Michael and Christopher Amott
Bauhaus - English gothic band, David J. and Kevin Haskins
Beach Boys, an American rock band, Brian, Carl, and Dennis Wilson
BeBe & CeCe Winans, American gospel music brother/sister duo
The Bee Gees, a British harmonic "soft rock" act, Barry, Robin, and Maurice Gibb
Biffy Clyro, a Scottish Rock Band, James Johnston & Ben Johnston
Blue October, Justin and Jeremy Furstenfeld
Boards of Canada, a Scottish electronic music duo consisting of brothers Mike Sandison and Marcus Eoin.
The Boswell Sisters, an American close harmony singing group, Martha, Connee and Helvetia "Vet" Boswell
Boyfriend, South Korean boy band with identical twins, Jo Youngmin and Jo Kwangmin
The Burns Sisters, folk/pop/rock trio with a Celtic slant
The Carpenters, American melodic pop duo, Karen and Richard Carpenter.
Cavalera Conspiracy, a Brazilian heavy metal supergroup, Max and Igor Cavalera
Cheeky Girls, a Romanian pop music duo, Gabriela and Monica Irimia
Chevelle, an American rock trio, Pete, Sam and Joe Loeffler
Collective Soul, an American Post-Grunge band, Ed Roland and Dean Roland
The Corrs, a Celtic folk rock band, Andrea, Sharon, Caroline, and Jim Corr.
The Cowsills, an American popular music family band. Bill, Bob, Paul, Barry, John, Susan, and mom Barbara.
Creedence Clearwater Revival, an American rock band, John Fogerty and Tom Fogerty.
The Cribs, indie rock band, Gary Jarman, Ryan Jarman & Ross Jarman.
The Darkness, an English rock band, Justin Hawkins and Dan Hawkins.
DEVO, an American new-wave band, Mark and Bob Mothersbaugh, and Gerald and Bob Casale.
Dixie Chicks, an American country music group Martie Maguire and Emily Robison.
The Everly Brothers, an American country-influenced band, Philip and Isaac Donald Everly.
Good Charlotte, an American pop punk band, Joel and Benji Madden
Haim - sisters Este, Danielle and Alana Haim
Halestorm, an American hard rock band, Arejay and Lzzy Hale.
Hanson, an American pop rock band, Isaac, Taylor, and Zac Hanson
Heart, an American rock band, Ann and Nancy Wilson
The Hives, Swedish Rock Band, Pelle Almqvist and Niklas Almqvist.
INXS had three Farriss brothers
The Jackson 5, an American popular music family group, Jackie, Tito, Jermaine, Marlon, and Michael Jackson
Brothers Johnny and Edgar Winter
Japan - English band, brothers David Sylvian and Steve Jansen.
Jonas Brothers, an American pop rock band, Kevin, Joe, and Nick Jonas.
Kalmah, a Finnish melodic death metal band, Pekka and Antti Kokko.
Kings of Leon, an American rock band, Caleb, Nathan, and Jared Followill.
The Kinks, an English rock band, Ray and Dave Davies.
Lamb of God, an American metal band, Will and Chris Adler.
The Maccabees, British indie rock band, brothers Felix, Hugo, and Will White.
Madina Lake, an American rock band, Nathan Leone and Matthew Leone
The Magic Numbers, an English rock band, Angela Gannon and Sean Gannon/Michele Stodart & Romeo Stodart.
Misery Signals, an American hardcore band, Brandon and Ryan Morgan.
The Moffatts, a Canadian pop/rock band, Scott and triplets Bob, Clint, and Dave. The fraternal twins Bob and Clint later formed a duo called Same Same.
My Chemical Romance, an American rock band, Mikey and Gerard Way.
Naked Brothers Band an American rock band Alex Wolff and Nat Wolff.
The National, an American rock band, Bryce and Aaron Dessner, Scott and Bryan Devendorf.
Nazia and Zoheb, were a Pakistani Pop group, Nazia Hassan, Zoheb Hassan.
Nickleback, a Canadian rock band, Chad, Mike and Brandon Kroeger.
No Doubt, an American rock band, Gwen and Eric Stefani.
The Nolans, an Irish/English family music group, Bernie Nolan, Anne Nolan, Maureen Nolan, Linda Nolan, Coleen Nolan, Denise Nolan.
October Tide, a Swedish metal band, Fredrik and Mattais Norrman
Oasis, an English rock band, Liam and Noel Gallagher
Olsen Brothers, Danish pop-rock duo
The Osmonds, an American family music group, Alan, Wanyne, Merrill, Jay, Donny, Marie, and Jimmy Osmond.
Pantera, an American heavy metal band, Dimebag Darrell and Vinnie Paul.
Paramore, an American rock band, Josh and Zac Farro.
Pierce the Veil, an American experimental post-hardcore band, Vic and Mike Fuentes.
The Pierces, an American folk-pop band consisting of sisters Allison and Catherine Pierce.
The Proclaimers, A Scottish Vocal Band, Charlie Reid and Craig Reid.
Radiohead, an English alternative rock band, Jonny and Colin Greenwood.
Sister Sledge, an American musical group, Kim Sledge, Debbie Sledge, Joni Sledge, and Kathy Sledge.
Stone Temple Pilots, an American grunge/alternative rock band, Robert and Dean DeLeo.
The Jesus and Mary Chain - English noise band, Jim and William Reid.
Tegan and Sara, Canadian indie band, Tegan Rain and Sara Kiersten Quin .
Tokio Hotel, a German pop rock band, Bill and Tom Kaulitz.
UB40, an English reggae band, Ali Campbell and Robin Campbell.
Van Halen, an American heavy metal/hard rock band, Eddie, and Alex Van Halen.
The Veronicas, an Australian electropop pop-rock duo, Jessica and Lisa Origliasso.
Rufus and Martha Wainwright.
The Wilson Family, an English folk music group composed of six siblings.
Wilson Phillips, an American pop group composed of sisters Wendy and Carnie Wilson, with Chynna Phillips.
YU grupa a Serbian rock band Dragi Jelic, Zika Jelic and Petar Jelic.
Young Guns, British rock band, brothers John and Fraser Taylor
Tasty, twin brothers So-ryong and Dae-ryong.
See also
Sibling relationship
Cousin
Twin
Triplet
Notes
Further reading
External links


Bibliography:
Wikipedia
@baygross