Nature, Nurture, & Human Diversity

By: Allen Widdifield, Jenny Kim, Emily Tharp

Twin Studies -Identical vs. Fraternal

Identical twins are developed from a single fertilized egg that splits into two are are genetically identical. Fraternal twins develop from separate eggs and are not genetically similar. Identical twin studies have provided a lot of information related to the nature/nurture debate. In cases where identical twins are separated near birth, regardless of environmental factors, they turn out virtually identical. In a case where two men, both named Jim, were separated 37 days after birth, they learned of each other during the middle of their life to find that they lives were strikingly similar. They both even had dogs named Toy and sons both named James.

Adoptive Studies

Adopted children have also provided a lot of information for the nature/nurture debate. Studies show that adopted children who grow up together do not resemble each other in personality. This begs the question of how much influence parents really have on their children. In adoptive homes, parents do affect their childrens' religion, manners, attitudes, and political views. However, they rarely are interested in the same things as their parents and siblings. In adoptive homes, child abuse, divorce, and child neglect are all very rare. Because of this, the adopted children usually score higher on intelligence tests than their biological parents, and are more mentally stable.
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Heritability is the extent to which variation among individuals can be attributed to their differing genes. Humans can not necessarily say what percentage of an individual's personality or intelligence is inherited. Heritability is the extent that genes make a difference on a person's attributes. With more similar environments comes less similar hereditary differences and vice-versa. People's personality is a combination of both nature and nurture. There is not necessarily a right or wrong answer when it comes to heritability.
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Parent Influences on Development

Parents feel pride and satisfaction when their child succeeds. In contrast, parents feel guilt and shame when their child fails. How much credit or blame do parents deserve? Studies such as Freudian psychiatry and psychology have been studying these ideas by blaming problems of asthma to schizophrenia on the parents. Parenting does shape the differences between children. The abused children become abusive and the loved and nurtured become self-confident and gregarious. Family also influences children's political view, religious beliefs, and personal manners. Although parents do shape their children, environmental factors also influences children. Developmental psychologist Sandra Scarr says, "parents should be given less credit for kids who turn out great and blamed less for kids who don't."

Gender Issues/Gender Roles

Gender, in psychology, is the biologically and socially influenced characteristics by which people define male and female.. People's gender is determined by twenty three pairs of chromosomes and two sex chromosomes. The two sex chromosomes are the X chromosome which is found in both men and women and the Y chromosome which is only found in males. Although our gender is biologically influenced, gender is also socially affected. Gender roles are a set of expected behaviors for males and for females. In the past, males roles were to work, drive the car, and pick up the check, and for females to stay home, cook, clean, and take care of children. Over the past years, gender roles have changed. Now, women can drive, make payments, and work. Society assigns each of us to a gender. The result is our strong gender identity, which is one's sense of being male or female. We also become gender-typed, which is the acquisition of a traditional masculine or feminine role. Some boys exhibit more masculine traits than others, and some girls are more distinctly feminine more than others. The Social learning theory assumes that children learn gender-linked behaviors by observing and imitating and by being rewarded or punished. Not only do parents reward their children, even without the parents, children organize themselves into "boy worlds and "girl worlds," each following rules for what boys and girls do.
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