twin studies are flawed

Get your science fix here: research, quackery, activism and all the rest
Post Reply
User avatar
Tessa K
Stummy Beige
Posts: 2797
Joined: Tue Nov 12, 2019 5:07 pm
Location: Closer than you'd like

twin studies are flawed

Post by Tessa K » 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.

https://web.archive.org/web/20201130032 ... 101623.pdf
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

User avatar
Boustrophedon
After Pie
Posts: 2257
Joined: Mon Nov 11, 2019 3:58 pm
Location: Lincolnshire Wolds

Re: twin studies are flawed

Post by Boustrophedon » Sun Aug 15, 2021 9:07 pm

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.
Put on your headlight and sound your horn if people get in the way. (Innes)

Allo V Psycho
Snowbonk
Posts: 460
Joined: Sat Nov 16, 2019 8:18 am

Re: twin studies are flawed

Post by Allo V Psycho » Wed Aug 18, 2021 8:45 am

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.

https://web.archive.org/web/20201130032 ... 101623.pdf
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.

User avatar
snoozeofreason
Fuzzable
Posts: 316
Joined: Fri Nov 15, 2019 1:22 pm

Re: twin studies are flawed

Post by snoozeofreason » Wed Aug 18, 2021 1:16 pm

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?

Post Reply