A gene is the general sequence of DNA, usually located in the same place on the chromosome in different individuals, which controls a given trait. An allele is a variation of this general sequence. Different alleles may give rise to different forms of a trait.

Heritability measures how much a trait is influenced by genes rather than by the environment.

Inbred strains have identical or nearly identical genetic information across individuals. This allows researchers to determine how much of a trait is genetically determined (remains the same across members of the strain) and how much is learned or environmentally influenced (can differ between members of the strain). The use of two different inbred strains in the same environment can also help determine the role of genetics in a given behavior.

Monozygotic twins arise from the same fertilized egg and thus have identical genetic material and are usually raised in the same environment. Dizygotic twins arise from separate fertilized eggs and differ in their genetic material, but are also usually raised in the same environment. Monozygotic and dizygotic twins are used to study human behavioral genetics rather than individual and pairs of inbred strains, respectively.

In a knockout study, a gene associated with a given trait is turned off or removed and the change to the trait is observed. These studies help show what roles specific genes play in a given trait.