Double Vision: Reply to Freese and Powell.

Freese and Powell make a number of critiques of the theoretical assumptions, statistical methods, and use of variables in our paper, which raises questions about the typical use of the equal environments assumption in twin research. We do not find that any of their critiques modify our conclusion that the equal environments assumption cannot be taken for granted but must be subjected to empirical testing. We hope that our paper and the resulting exchange will lead sociologists to become more actively involved in the debate regarding the extent of genetic and environmental influences on social behaviors. [ABSTRACT FROM AUTHOR]