behavior genetics
the study of the relative power and limits of genetic and environmental influences on behavior
environment
every nongenetic influence, from prenatal nutrition to the people and things around us
identical twins
twins who develop from a single fertilized egg that splits in two, creating two genetically identical organisms
fraternal twins
twins who develop from separate eggs. They are genetically no closer than brothers and sisters, but they share a fetal environment
interaction
the effect of one factor (such as environment) depends on another factor (such as heredity)
culture
the enduring behaviors, ideas, attitudes, and traditions shared by a large group of people and transmitted from one generation to the next
norm
an understood rule for accepted and expected behavior. Norms prescribe "proper" behavior
personal space
the buffer zone we like to maintain around our bodies
temperament
a person's characteristic emotional reactivity and intensity
chromosomes
threadlike structures made of DNA molecules that contain the genes
DNA deoxyribonucleic acid
a complex molecule containing the genetic information that makes up chromosomes
genes
the biochemical units of heredity that make up the chromosomes; a segment of DNA capable of synthesizing a protein
natural selection
the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations
evolutionary psychology
the study of the evolution of behavior and the mind, using principles of natural selection
gender
in psychology, the biologically and socially influenced characteristics by which people define male and female
mutation
a random error in gene replication that leads to a genetic change
X chromosome
the sex chromosome found in both men and women. Females have two X chromosomes; males have one. An X chromosome from each parent produces a female child.
Y chromosome
the sex chromosome found only in males. When paired with an X chromosome from the mother, it produces a male child.
testosterone
the most important of the male sex hormones. Both males and females have it, but the additional testosterone in males stimulates the growth of the male sex organs in the fetus and the development of the male sex characteristics during puberty
role
a set of expectations (norms) about a social position, defining how those in the position ought to behave
gender role
a set of expected behaviors for males and for females
gender identity
one's sense of being male or female
gender-typing
the acquisition of a traditional masculine or feminine role
social learning theory
the theory that we learn social behavior by observing and imitating and by being rewarded or punished
gender schema theory
the theory that children learn from their cultures a concept of what it means to be male and female and that they adjust their behavior accordingly