alt Hacker NewsI don't have an opinion to offer here other than the intrinsic limitations of studies that depend on twins raised apart (that there aren't many of them). It's an unusual instance of a stat where the obvious concern with the premise is underappreciated rather than overappreciated. I've got nothing on MZ/DZ controls.
ah I see, you're commenting on the general difficulty, not necessarily saying this study's results are bad due to the limitation. My apologies, I don't think we disagree.