Emphasizes the importance of adaptation, reproduction, and "survival of the fittest" in shaping behavior.
Threadlike structures that come in 23 pairs, one member of each pair coming from each parent. Chromosomes contain the genetic substance DNA.
Units of hereditary information composed of short segments of DNA. Genes direct cells to reproduce themselves and manufacture the proteins that maintain life.
Cellular reproduction in which the cell's nucleus duplicates itself with two new cells being formed, each containing the same DNA as the parent cell, arranged in the same 23 pairs of chromosomes.
A stage in reproduction whereby an egg and a sperm fuse to create a single cell, called a zygote.
The way an individual's genotype is expressed in observable and measurable characteristics.
A chromosomally transmitted form of mental retardation, caused by the presence of an extra copy of chromosome 21
A chromosomal disorder in which males have an extra X chromosome, making them XXY instead of XY.
Fragile X syndrome
A genetic disorder involving an abnormality in the X chromosome, which becomes constricted and often breaks.
A chromosomal disorder in females in which either an X chromosome is missing, making the person XO instead of XX, or part of one X chromosome is deleted.
A genetic disorder in which an individual cannot properly metabolize phenylalanine, an amino acid. PKU is now easily detected byt, if left untreated, results in mental retardation and hyperactivity.
The field that seeks to discover the influence of heredity and environment on individual differences in human traits and development.
A study in which the behavioral similarity of identical twins is compared with the behavioral similarity of fraternal twins.
A study in which investigators seek to discover whether, in behavior and psychologica characteristics, adopted children are more like their adoptive parents, who provided a home environment, or more like their biological parents, who contributed their heredity. Another form of the adoption study is to compare adoptive and biological siblings.
Passive genotype environment correlations
Correlations that exist when the natural parents, who are genetically related to the child, provide a rearing environment for the child.
Evocative genotype environment correlations
Correlations that exist when the child's genotype elicits certain types of physical ad social environment.
Active genotype environment correlations
Correlations that exist when children seek out environments they find compatible and stimulating.
Shared environmental experiences
Siblings' common environmental experiences, such as their parents' personalities and intellectual orientation, the family's socioeconomic status, and the neighborhood in which they live.
Nonshared environmental experiences
The child's own unique experiences, both within the family and outside the family, that are not shared by another sibling. Thus, experiences occurring within the family can be part of the "nonshared environment".