I had other studies in mind (done in China) regarding that specific point, it's what I had assumed a lot of posters here were referring to because it's normally

I had other studies in mind (done in China) regarding that specific point, it's what I had assumed a lot of posters here were referring to because it's normally a favorite of people who are eager to jump to certain conclusions about genetics. There are other problems with twin studies, most importantly that developmental health starts at conception which means that genetics are not the only thing that twins are sharing. Once again I'll refer you to Wikipedia for further criticisms of twin studies: https://en.wikipedia.org/wiki/Twin_study#Criticism https://en.wikipedia.org/wiki/Twin_study#Criticism