[mikorym]

I have some background to understand this (bioinformatics Honours), but am not an expert. What I can say is that the study at this point, if based on DNA methylation, does not even suggest that the effect is of physical contact is positive (to be Devil's advocate, the DNA methylation from physical contact could have a negative effect).

The study does ask for indicators (crying, behaviour, etc.) but with those parameters you can already try to correlate a lot of physical contact vs. less contact.

They are trying to tell whether methylation is worth studying (at all) in the context of more vs. less contact with your child. Personally, for the purposes of raising a child, I don't think these studies say anything at all. It's more important to stop panicking about nonexistent threats that social media wackos will try to convince you of.

Epigenetics is a very interesting field of study and is like a downtuned Lamarckian inheritance all over again. Things like chronic inflammation are still far from well understood. The body is like having 2 000 000 000 years of Wikipedia and all its edit history crammed into one string of DNA letters. And now we learn that apparently metadata (the DNA methylation) is also crammed into the whole thing and even that changes all the time.

By the way, for that matter, what constitutes "affectionate physical contact" quantitatively is not clear to me. I think each child's particular emotional need at any time is really difficult to pinpoint. I had a great childhood and parents, but I think that I always had a sort of angst (maybe competitive angst?) that really can't be said to be anyone's fault. These days if you feel funny and go the psychologist they will probably say: "Don't worry. It's just appropriate affect. If you spend 15 hours a day on Instagram then you are supposed to feel funny."