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Epigenetics: Are all those twin studies just a big racket?

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We are told that twins show differences at birth. So why are twin studies that supposedly identify the gay gene or the religion gene not just another big social studies racket?

Human twins are not bacteria colonies. The reasons why one or both are even available for adoption must be factored in to any findings.

How many families leave a twin behind at the hospital, for someone else to bring up, because they only wanted one kid?

How many adoptive parents wouldn’t just grab a chance to acquire both, if offered?

If they are infertile to begin with, which is why they are in the market anyway, two-for-one is actually a solution, not a problem.

And then they don’t have the problem, either, that one of the kids is being raised by someone they don’t know, and their own kid wants to get in touch, and then there’s the birth mother too, yada, yada, maybe a birth father, yoo-HOO!! To who?

If you like soap operas, you’ll love the chance to live in a really complex plot, involving all kinds of people who made decisions you never would have. Otherwise, you might perhaps want to discreetly acquire both twins, to reduce the complexity somewhat.

No, seriously, not enough attention is being paid to the social circumstances under which a pair of twins comes up for separate adoption. Surely that affects everyone involved.

But now, what about this epigenetics thing? Doesn’t that just slam the whole genetic determinist gene business (gay gene, fat gene, infidelity gene, religion gene) into the dumpster?


The issue with twin studies vis a vis genetic determinism is that it puts an upper bound on what is genetically determined. Actually, if it puts on any bound, then it's a lower bound (because it only estimates additive genetic variance, not total genetic variance). Your larger point, that there are multiple causes,is correct. People working in genetics know this, of course, so don't discuss it, so I think this gets lost in simplified presentations of genetics. A Gene
This is largely correct. The issue with twin studies vis a vis genetic determinism is that it puts an upper bound on what is genetically determined. It is, and has always been, wholly irresponsible and irrational to jump from 'this is the maximal input due genes' to 'this is the sole cause'. The separate issue of epigenetics is to demonstrate again this cautionary tale: That you cannot speak of the 'only cause' until you have exhaustively found all of the 'only' causes. Maus
Are you saying that the environment effects the epigenome which produces a gay twin? Also, if that is true, does that mean it can or cannot be changed back? ForJah
I don't see the relevance of adoption - twin studies are usually carried out by comparing mono- and di- zygotic twins: the idea is to have individuals who experience the same environment (or at least one that is as similar as possible). A Gene
ForJah, some of us question twin studies for several reasons, one of which is addressed in the post: The idea that twins just happen to get separated. Twins do not just happen to get separated. So it's probably a non-standard environment to begin with. There are other issues as well, like who decides who gets a kid to raise. News
Why would epi-genetics slam the gay gene or any other gene you just described? In fact, it seems it would benefit it in an opposite way. Researchers, specifically Christians, say there is no gay gene because of identical-twin studies. These studies are based on the premise that since the genes are the same than both twins should turn out gay. Since some twins do NOT turn out to be gay, the idea that it's genetic is untrue. BUT if epigenetics tells us that identical twins are actually different than that makes all those studies faulty, because they were based on the false premise mentioned above. ForJah

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