chapter  3
Studies of Reared-Apart Twins
The Critics Respond
Pages 14

This chapter examines the arguments of several critics of TRA studies. It describes the most in-depth work ever published on the subject, and contained a wealth of thoughtful discussion and detailed statistical analysis. The groundwork for much of the analyses of the Newman, Shields, and Juel-Nielsen studies was laid by earlier authors such as Leon Kamin, Susan Farber, Howard Taylor, Arthur Goldberger, Richard Lewontin, Ken Richardson, Richard Rose, Steven Rose, and others. Taylor wrote that roughly two-thirds of the pairs studied in the three classical TRA studies 'do not fit any reasonable definition of being raised separately in uncorrelated environments'. British psychologist Ken Richardson questioned the degree of twin separation in TRA studies, and pointed to the fact that many MZAs were reared in different branches of the same family. Of the 121 cases reported in the last fifty years, wrote Farber, only three are 'twins reared apart' in the classical sense.