to preempt common criticisms: 1) 99% is not unbelievably high, given that they used factor analysis to improve the reliability of the measurements 2) this does

to preempt common criticisms: 1) 99% is not unbelievably high, given that they used factor analysis to improve the reliability of the measurements 2) this doesn't preclude a) environmental influences that interact with genetic profiles nor b) environmental influences which act on the mean value of a twin-pair's score (the study's concerned with deviations from means within twin pairs). thanks for the interest guys.