Notes

Hereditary Factors:

The offspring of animals, plants, and people resemble their parents. In essence, they inherit the physical attributes of their creators. If both parents have blond hair, it is likely that their child will also have blond hair. This phenomenon is called heredity. It occurs because parents pass on certain traits to their offspring. An individual’s traits include characteristics such as eye color, shape of the nose, hair texture, and so on. These characteristics are not limited to physical traits. They also include traits such as behavior, intelligence, and personality.

Gregor Mendel was known as the father of genetics. In the mid-1800s, he conducted experiments on pea plants to study the mechanism of heredity. He discovered that the various traits of an individual were an expression of a part of each cell within the individual’s body. These parts are the individual’s genes. Mendel’s discoveries helped establish the branch of science known as genetics. Genetics attempts to understand the genomes of all living things. It also attempts to explain how various genes define different aspects of organisms.

Genes and Traits:
A genome consists of deoxyribonucleic acid (DNA). Sequences of DNA called genes control the development of traits in a person. Ribonucleic acid (RNA) is responsible for coding, decoding, regulating, and performing other functions in a cell. This controls the development of traits.

All living organisms contain both DNA and RNA in their cells. The genes in DNA contain instructions that control the development of the organism. In humans, genes control the development and function of various organs, physical attributes, and (to some extent) behavioral aspects.

Genotype refers to the genetic makeup of an individual. Phenotype is the expressed traits of the individual. Multiple genes may be involved in the expression of a single trait. For example, skin color or blood group. Such groups of genes are called polygenes.
Inheritance
Inheritance or heredity is an important concept explained by genetics. It sheds light on why offspring resemble their parents. When individuals reproduce, they pass their genetic material on to their offspring. Let’s look at an example. Adam has black eyes, and so does his father. Adam’s mother has blue eyes. The genes Adam received from his parents would have the instructions for black eyes (from his father) and blue eyes (from his mother). In Adam’s case, the gene for black eyes is expressed over the gene for blue eyes. An examination of Adam’s genetic makeup would show that he has both genes (for black and blue eyes) from his parents. However, the gene for black eye color is dominant. The gene for blue eye color is recessive. Thus, Adam inherited the trait of black eye color from his father.

The traits that Adam inherited from his parents represent one possible outcome in the given scenario. Other outcomes are also possible. For example, Adam’s father could have received a recessive blue eye gene from his parents. If Adam's parents decide to have another child, this child may receive a gene for blue eyes from the father and the mother. In this case, Adam's sibling would have blue eyes.
e Genetic Influence
Various physical traits are attributed to genes. These may include height, eye color, hair color, and hair texture. Individuals might even inherit certain diseases, such as Huntington’s disease or sickle-cell anemia, from their ancestors. They also inherit other features from their parents. For example, blood group.

Recent studies show that genetics might influence an individual’s personality traits as well. Traits such as self-control, decision making, and sociability are shaped by genetic information inherited from one’s parents. There are conflicting viewpoints on whether traits such as aggression are genetically determined. Some psychologists attribute aggression to genetic factors. Others state that individuals acquire such traits through their environment during childhood.
An individual’s eye color is completely determined by genes inherited from the parents.

Environmental Influences:
Various factors influence an individual’s growth and development. Physical traits, such as hair and skin color, are predetermined at conception. However, behavioral aspects develop during an individual’s early childhood and depend on the individual’s environment, or nurture. Environment includes various factors such as nutrition, caregiving or parenting, social and economic conditions, and education. These factors influence your behavior, personality, and intelligence during your formative years. In essence, environmental factors play a crucial role in an individual’s development process.

Nutrition:
The nutrition that an individual receives during intrauterine life (before birth) and in the first five years of childhood is very important. The first few years are when much of the brain’s development occurs. Proper nutrition will affect the individual’s future health as well as the person’s ability to learn, communicate, analyze, socialize, and adjust to new environments. Malnourished children tend to have problems related to behavioral development. They also have cognitive development and reproductive health problems. Additionally, they may also suffer from delayed physical growth and motor development, lower IQ, inability to concentrate, etc.

Environmental Influences:
Various factors influence an individual’s growth and development. Physical traits, such as hair and skin color, are predetermined at conception. However, behavioral aspects develop during an individual’s early childhood and depend on the individual’s environment, or nurture. Environment includes various factors such as nutrition, caregiving or parenting, social and economic conditions, and education. These factors influence your behavior, personality, and intelligence during your formative years. In essence, environmental factors play a crucial role in an individual’s development process.

Caregiving and Parenting:
A stable, secure, and supportive environment at home is conducive to the well-being and all-around development of a child. Caregivers, who are most often the parents, are the child’s primary educators. Their behavior and attitude, along with the home environment, plays a crucial role in a child’s development.

Intellectual stimulation and parent-child discussions lead to personal fulfillment for a child. The relationship between the parents as well as the relationship between the child and the parents can significantly affect a child’s emotional and cognitive development. The parenting style can also influence a child’s development. A negative parenting style may have adverse effects on a child’s emotional growth.

The psychologist Albert Bandura’s bobo doll experiment illustrates how children learn behavioral patterns through observation. This experiment suggests that children can learn a specific social behavior, such as aggression, by observing others. Children whose parents hold, hug, or smile at them and participate in their activities tend to feel more secure and better adjusted.
Culture
A child’s community, society, and lifestyle can also affect behavior and personality. Various cultural aspects, such as upbringing, schooling, peer groups, religion, and social setting all influence a child’s activities and behavior. For example, if a child belongs to a culture that restricts public displays of affection, the child may eventually conform to this cultural trait as an adult.

Community trends influence an individual’s language, clothing, and even career path. The social setting, institutions such as schools, and peer groups also affect a child’s development. By the age of four, children tend to form social groups and learn behavior through imitation.

Education:
The education a child receives also affects the child’s emotional, cognitive, and physical development. Children enrolled in preschool tend to perform better in grade school because of their early exposure to learning and acquisition of the social skills necessary to perform at higher levels. Preschools introduce children to social interaction, help them develop peer skills, and facilitate emotional growth.
s is the case with genetic factors, numerous research studies have tried to determine the extent to which environmental factors affect an individual’s growth and development. Studies have shown that environmental factors also influence inherent traits. For example, factors such as nutrition can significantly affect the health of a growing child. Children who do not obtain adequate exercise or nutrition tend to have stunted growth. This happens regardless of their genetic makeup.

Good education, a positive parenting style, and healthy cultural influences help individuals develop favorable social characteristics and interpersonal skills. Such children tend to be better at expressing themselves emotionally. Children who receive proper stimulation and exercise during the development of their brain synapses and pathways tend to be more imaginative and creative. In contrast, negative influences tend to interfere with a child’s mental and emotional development. Some negative influence could include negligent parents, low income, malnutrition, a restrictive culture, and bullying.
Parents’ sincere involvement can positively influence a child’s development.
The Heredity Versus Environment Debate
Both heredity and environment play major roles in the development of individuals. An individual with a genetic bias for certain traits will develop those traits. These may be physical, behavioral, or personality traits. During the developmental phase, the environment also shapes a child’s growing mind and certain physical characteristics. This may be in the form of parenting and stimuli.

Does heredity have a greater influence than the environment in determining an individual’s traits? Which traits does each aspect determine? Earlier psychologists believed that only genetics contributed an individual’s physical traits. They felt that environmental factors were responsible for behavior and personality. Subsequent studies and research discovered that genetics could affect certain behavioral traits and environmental factors could influence certain physical traits. Thus, heredity and environment may encroach on each other’s domain of influence.

In this debate, psychologists who believe that heredity plays the dominant role in an individual’s development take the side of nature. Other professionals in the field argue that an individual’s environment, or nurture, plays a bigger part in a person’s overall growth.

The Arguments:
Both sides in the nature versus nurture debate have strong arguments in favor of genetics or the environment as a major factor in shaping an individual’s traits. Some psychologists have extreme views. They believe that all traits are expressions that are hard-coded in an individual’s genes or genome at conception. Psychologists with this point of view are called eugenicists. They argue that certain characteristics are not evident at birth and may appear during later stages of an individual’s lifespan. However, the genes for such traits must already exist within the person’s genome.

This point of view leads to the conclusion that a good parenting style or a stimulating external environment does not matter. An individual’s traits solely rely on genes passed on by the parents.
n the other side of this argument are euthenists. These psychologists believe that while genetics may play a major role in determining individual physical traits, other traits are shaped after conception, independent of the individual’s genetic predisposition. These traits include individual’s behavioral traits, personality, and intelligence. Certain physical characteristics may be determined to a certain extent after conception.

Euthenists believe that, given a positive environment, all humans have the potential to grow in terms of intelligence, behavior, and personality. They also argue that a child with positive genetic traits may not achieve such potential under adverse environmental conditions.

The Evidence:
Researchers have conducted various studies to settle the debate of nature versus nurture. Determining the influence of environmental factors is a difficult task. One reason is that different individuals have different inherited traits. This makes it difficult to repeat experiments under identical situations. In addition, it is difficult to compare environmental influences on different individuals. Three types of studies have tried to identify the factors that affect development:

Family studies: Such studies evaluate children during their developing years. They detect traits that the children may have inherited genetically from their parents. The downside of family studies is that they do not isolate traits that could be ambiguous. For example, children with overweight parents may be overweight not for genetic reasons. The reason may be because they follow their parents’ eating habits.

Adoption studies: These studies follow adopted children and study them during their developing years. Researchers can thus observe hereditary traits that pass on from the biological parents to the children. They can also study the influence of environmental factors in the foster parents’ homes.

Twin studies: These studies observe twins to study the effects of hereditary and environmental factors. They study both identical as well non-identical twins. Identical twins share exactly the same genome, but non-identical twins do not.
Separated Twin Studies
Studies conducted on identical twins have provided great insights on the environmental development of children. Studies were conducted on twins who were separated at birth and adopted by different families. This presented an opportunity to study the environmental influence on the development of such children. Both the test subjects are predisposed to share the same traits because of their nearly identical genetic makeup. However, they experience different environmental influences. These studies show how environmental factors can influence an individual’s development.

A famous study of separated twins is that of Amy and Beth. Both these girls were raised by different families. Amy’s family was poor. Beth’s family was rich. Amy’s adopted family did not integrate her well. However, Beth’s family treated her as one of their own. When the twins reached the age of 10, aside from minor differences, the girls had similar personalities. They were both shy, troubled, afraid of the dark, and lonely. Thus, even though the twins’ environments were starkly different, their personalities were similar. This suggests that they were genetically predisposed to their personalities.
Cases of separated twins who remain isolated from each other are difficult to find. There are a few studies conducted on separated twins. The results of these studies have shown a high possibility of similar traits. This suggests that genetic factors have a significant influence on individuals. This also shows that the environment plays a relatively minor role in shaping individual traits. Critics of such studies state the findings are not conclusive. They point to cases in which two unrelated individuals develop similar traits.

Another criticism of studies involving twins is that they are not representative of the larger population. They consider only a small group chosen from a non-random population. Therefore, one cannot generalize such studies and apply them to the entire population. Also, such studies are unable to account for all the variables that determine an individual’s development. In addition, it is not possible to measure the influence of one variable (such as the environment) while keeping all other variables constant

The Conclusion:
Geneticists cite the study of the human genome to help them map traits to specific genes or polygenes. These traits include both physical and behavioral traits. They argue that if an individual has a genetic predisposition to a particular behavioral trait, the environment has little or no effect on the trait’s expression. Supporters of environmental influence cite examples of individuals with different genetic make-ups expressing similar behavioral traits due to similar environmental influences. Both camps have reconciled their points of view. This is because studies support both sides of the argument. In conclusion, one can state that an individual with a genetic disposition to a certain trait would express the trait if it were nurtured by environmental influences during the person’s formative years. It is also possible to suppress an individual’s undesirable behavioral traits. You can do this by providing positive environmental influences. However, this will not erase or lessen the individual’s genetic predisposition.

Over the years, psychologists have shifted the debate of heredity versus environment to that of heredity and environment. This acknowledges that both play a significant role in the development of an individual. Eugenicists and euthenists believe that there are more than just black-and-white shades to human development. Both components play an important role at different stages. They influence different aspects of an individual’s development.
Traits such as hair, eye, and skin color are inherited from the parents, while traits such as sociability and fashion sense are mainly developed due to environmental influences.