Family studies fail to rule out the extent to which environmental factors influence certain traits.To separate the effects of heredity from those of environment,researchers do

A) twin studies.
B) experimental studies.
C) adoption studies.
D) longitudinal studies.

Adoption studies allow researchers to compare the similarities and differences between biological relatives (who share genetics) and adoptive relatives (who share environment) in terms of certain traits. This helps to separate the effects of heredity from those of environment. Twin studies also help in this regard but are limited in that they only consider the similarities and differences between identical and fraternal twins (who share varying degrees of genetics and environment). Experimental studies and longitudinal studies may also provide some insight into the effects of environment on certain traits, but they are not specifically designed to separate the effects of heredity and environment.