Behavior genetics explores the role of inheritance in shaping human behavior. Researchers use family, twin, and adoption studies to assess heritability by examining traits among relatives, helping to determine the role of genetics and environment in these traits. In family studies, researchers track traits within biological families to identify genetic influences on behaviors such as depression or intelligence. This approach may reveal behavior patterns and potential genetic risks. Twin studies involve comparing identical twins, who share 100% of their genes, with fraternal twins, who share about 50%. Identical twins typically show greater similarity than fraternal twins. For example, twin studies show that identical twins have more similar IQ scores than fraternal twins. Adoption studies investigate the effect of genetics and environment in shaping the behavior of children raised by adoptive parents. For instance, if a child's biological mother is outspoken and cheerful, and the child has similar behavior despite being raised by introverted adoptive parents, it suggests that extrovert behavior is influenced by genetics.