Thus, for Extraversion, there are qualitative sex differences in the additive and non-additive genetic effects, but the additive and non-additive genetic effects are of equal magnitude in males and females: 24 % and 25 %, respectively. The χ2 statistic for these qualitative sex differences was relatively small given the large sample size, but nevertheless, the opposite sex twin correlation was a factor 0.76 smaller than expected under no qualitative differences (i.e., 0.14 instead of 0.18).
