Psychology Chapter 4 Key Terms
Behavior Genetics – the study of the relative power and limits of genetic and environmental influences on
Environment – every nongenetic influence, from prenatal nutrition to the people and things around us.
Chromosomes – threadlike structures made of DNA molecules that contain the genes.
DNA (deoxyribonucleic acid) – a complex molecule containing the genetic information that makes up the
Genes – the biochemical units of heredity that makes up the chromosomes; a segment of DNA capable of
synthesizing a protein.
Genome – the complete instructions for making an organism, consisting of all the genetic material in that
Identical twins – twins who develop from a single (monozygotic) fertilized egg that splits in two, creating two
genetically identical organisms
Fraternal twins – twins who develop from separate (dizygotic) fertilized eggs. They are genetically no closer
than brothers and sisters, but they share a fetal environment
Temperament – a person’s characteristic emotional reactivity and intensity
Molecular genetics – the subfield of biology that studies the molecular structure of functions of genes
Heritability – the proportion of variation among individuals that we can attribute to genes. The heritability of a
trait may vary, depending on the range of populations and environments studied
Interaction – the interplay that occurs when the effect of one factor (such as environment) depends on another
factor (such as hereditary)
Epigenetics – the study of influences on gene expression that occur without a DNA change
Evolutionary psychology – the study of the evoluti