I'd guess the idea of this study is not that having a child of your own somehow directly alters your brain biologicaly, but the experience itself is just that intense. I find it much more interesting, the fact that most of the changes mother experiences might not be the "nature's wonder", but lasting, painful, traumatic and exciting experience itself that affects one's brain.

Edit: And that itself has much deeper relation to a biological child than to adopting one. Not that adopting isn't significant or emotional, it's simply not that varying level of experience.

> Another curious question, it would be interesting to see the impact of adopting a cat or a dog on men’s testosterone levels.

I would compare this analogy to the opposite and unfortunate experience like the death of a close one. Losing someone that's biologically linked to you can be really hard even if you weren't that emotionally attached to that person. By comparing that to losing a friend outside of your family circle, which is also a very harsh experience, it seems that biological line would be an emotional line deeply attached to a person no matter what experience one has.

When conceiving children biologically, if you do not have reason to believe your partner has had sex with other men, the natural assumption is that the child is yours.

Also, family resemblances do exist. Their absence doesn't disprove parentage, but their presence is evidence for it.

When adopting, if you were not sexually active prior to adoption and have not donated sperm, you can be certain the child is not biologically yours. Even if you were active or a donor, you can still be very confident the kid is likely not yours.

I think adoption is a wonderful thing and I am not trying to undercut it, but it seems entirely possible to me that those differences could impact the bond between a father and child.

Exactly. Stating that an adoption is same as having a child of your own, is going against all empirical evidence that a person has great emotional changes upon finding out about your own biological relation to someone. Maybe it is entirely psychological, but idea of a biological relation affects a person a great deal.

I think most of the confusion here is coming from the idea that psychology can't be related to biology. However, I firmly believe that biology is the base of the psychology and you cannot alter psychology without altering the biology itself.

If i recall correctly, men who are bonded (via sex of course given the huge oxytocin releases) to their childrens mother and who saw the mother throughout pregnancy and were sure there was no cheating have a higher affinity to that child and this can be measured hormonally. Its not 100 percent but probably good enough for natural selection. Also marriage and pair bonding is rather common among our closely related primate brethren

Edit: also the testosterone stuff is mostly a myth in the sense that, while testosterone of new fathers drops, it also recovers some months after the baby is born and older. So you get some months of baby snuggles and then you're back with your old libido. Also, men with kids are way more attractive to women (including their wives) anyway.

I explicitly stated that experience of biologically delivering a child is affecting both of parents, NOT on a biological basis but strictly on the level of THE experience itself. I could have been clearer by stating "biologically delivered child by mother", instead of the "biological child", but I have not, in any sense, reffered to a biological child-father connection being relevant to anything.

What may have confused you is that I stated that the idea of being biologically related to someone, has a mental effect that creates some emotional attachment - yes, due to the biological relation as a social construct. That was an additional idea to compare it to adopted cat/dog/child analogy.

Trivial option: if cohabitating with the mother, I could see pregnancy having effects (via pheromones, or just behavior) that would be completely skipped over by adoption. Obviously it's not strictly a "does this child have 50% of my DNA" thing, but it does differentiate between biologically having a child and adopting.

Typical non-paternity rate among people with self-reported high-confidence in paternity are around 2%. (That’s much higher than I’d have thought, but lower than the commonly cited 10% figure, which is driven by a selection bias in who takes paternity tests in the overall case.)

> But all of this fathering thing is related with continue one's bloodline I guess.

Can I safely assume you haven't adopted any children? I'm a parent of two adopted kids (now mostly grown). If you think what motivates me is any different than what motivates other fathers, you would be terribly mistaken.

And here is my turn to speak without knowing: I imagine that if a father is too attached to the idea of the continuation of his genetic legacy, it may pressure the children to fulfill the father's idea of a legacy rather than find their own path.