most pairs were only partially reared apart ... the studies used flawed designs based on other questionable or false assumptions, were methodologically flawed in many additional respects, and the researchers’ conclusions were strongly influenced by genetic confirmation biases
My first though on reading the title was "Cyril Burt" and to wonder how many other studies were left after deleting his.
I took somewhat devilish delight in quoting Burt and his studies in my essays when doing my PGCE knowing that my supervisors was entirely unaware of the debunking of Burt's work that was still on going at the time.
Tessa K wrote: Sun Aug 15, 2021 8:33 pm
I haven't had time to read all of this yet but it looks interesting. Many influential studies of identical twins reared apart are very flawed.
most pairs were only partially reared apart ... the studies used flawed designs based on other questionable or false assumptions, were methodologically flawed in many additional respects, and the researchers’ conclusions were strongly influenced by genetic confirmation biases
Indeed. And I think he could lay even more emphasis on epigenetic factors during pregnancy - the Barker hypothesis, sometime less eponymously called developmental origins of adult health and disease.
Suzuki, K., 2018. The developing world of DOHaD. Journal of developmental origins of health and disease, 9(3), pp.266-269.
There are also the ideas of hormonal and epigenetic influences in pregnancy influencing sexuality, a la Simon Baron-Cohen.
He does touch on the assumption that all genetic effects are additive, which seems to me (as a non-biologist) to be a fundamental Achilles heel in studies involving MZ twins, because the non-additive effects aren't necessarily "heritable" in the ordinary language sense of being likely to form part of the phenotype of ones descendants.
In six days the Lord made the heavens and the earth, the sea, and all that is in them. The human body was knocked up pretty late on the Friday afternoon, with a deadline looming. How well do you expect it to work?
