Babies who get more cuddles have their genetics changed for years, study shows

There are multiple reasons that could have happened: one is that the scientists didn't think of it (which to me would undermine their credibility as it is really obvious as a possibility), a second is that this study was much cheaper and they weren't sure there would be a correlation at all (so now there is enough evidence to warrant a better study), and a third is that they didn't care about "why" and were only interested in "that".

To the scientist's credit, the article quotes them as saying that they don't know the cause, which is great, and they say "too early" so they might intend to keep going. To their discredit, they gave enough of an explanation based on stuff they weren't sure of to the reporter to guide it to the point where the headline is just guesswork, not real science.

On the other hand, you certainly... and apparently the scientists :/... are simply assuming your explanation and then using a study that is incapable of discerning the the difference between these two hypotheses to dismiss the idea, which is clearly not OK.

[I am sorry if someone saw a draft of this comment or if it appeared under the wrong parent for a moment: I was having issues replying on my iPhone today :/.]

Not at all. What I am saying is a standard criticism of overhyped epigenetics studies which follows from the lazy design which does not control for very large known confounds (pretty much all effects are smaller in a within-family comparison) or actually demonstrate it's not reverse causation, which as in OP results in such wild overhyping of causal implications. This is as much 'zero effort' as noting, of the latest nutrition study claiming that fat (or carbs, or red meat, or protein, or milk, or eggs, or...) will definitely kill you, that the methods simply do not work for what they are claimed to prove. If you find the criticisms tiresomely cliche & predictable, that's an indictment of the researchers or funders, not the criticisms. (I know I find it tiresome to point out the same problems every time and respond to comments shocked that correlation!=causation, or that most human traits are heritable, or that p-values mean nothing interesting, estimates are inflated by publication bias, one shouldn't control for intermediate variables, gains fade out etc. I suppose I do it out of stubborn perversity. I keep resolving not to get into arguments about these things, and keep failing.)

It has been demonstrated many times that epigenetics are heritable, affected by gene-environment correlations, and are not themselves causal for many outcomes they have been claimed to be but passive indicators of environment; so OP is, at best, possible but not probable and the speculation that the epigenetics changes will have any causal effects later on to be taken with considerable skepticism... (as they are more likely to simply indicate the manifestation of the childrens' genes as inherited from their parents). Epigenetics is of tremendous biological interest as it is often how genetics exerts its effects, but unfortunately, that's not what people want epigenetics to be. You may remember the scientific reaction to Siddhartha Mukherjee's New Yorker article on epigenetics last year which similarly took likely-confounded & reverse causation epigenetics claims at face value.

For sleep training? It’s a somewhat rough 2-7 nights when they’re in the 8-12 week age range, or way, way worse later and a ton of bad nights until then. Probably some kids don’t take to it, but that’s true of anything you try. We’re 3-for-3 on it, with the worst taking three nights. A+++++, would not accustom my kids to someone coming in and rescuing them from learning how to chain REM cycles every time they wimper again. Only way I’ve seen it go wrong with ours or with friends’ kids is 1) inconsistency on the part of the parents, or 2) illness getting in the way.

With modern insight it seems more likely that moms somewhere on the autism spectrum themselves were being blamed because they seemed odd to neurotypical medics.

https://en.m.wikipedia.org/wiki/Refrigerator_mother_theory