>Does it really matter whose child it is?

Umm what? Do you not see the inherent breakage of trust if your wife is having sex with someone else in a monogamous relationship and then trying to pass off someone else' kid as yours?

It doesn't matter for this story of contraception not working 100%.

> Does it really matter whose child it is?

I'm not sure I understand. Are you asking why it matters for a man to unknowingly raise another man's child, which his wife conceived while being unfaithful to him?

1) You seem to have totally focused on the "parent" role, and forgotten the "partner" aspect. This has major implications for the relationship.

2) The practical difference is choice. Biological parents are pretty stuck. People in this situation aren't at all.

Nope. Once you have kids being the parent is the most important thing.

How is raising someone else’s child a moral obligation? If a man’s wife has a child with her lover her lover has an obligation to raise the child. He’s the father. The mother’s husband has no relation to the child.

We should note that, yes, being the parent is the most important thing, but the quality and effort put into the partnership has a substantial effect on the quality of the parenting.

It's a question of trust, for starters?

So what is the test that the husband should undergo? I mean why only think about the faithfulness of the wife?

A woman always knows that the child is hers. It's not a symmetrical issue

Yes! Especially several years later. Stupid shit happens, to all of us. And if the kid has 'adopted' the father, then for many years it will be outright traumatic to cut the relationship and trust if that kid just because if some test. Oh, not my DNA, then I don't love you? How narcissistic of a father would that be? Joseph of Nazareth would like to have a word, too...

No, there should be very good and compelling reasons to request a DNA test.

Making a man raise someone else’s child is not “stupid shit”. It is a calculated major betrayal.

If Joseph chose to raise someone else’s child that’s nice for him. Great. He made a morally laudable, superogatory choice. That’s very different from being betrayed by your loved one and deceived into raising someone else’s child.

> Joseph of Nazareth would like to have a word, too...

Joseph was going to "divorce her quietly"[1] until an angel intervened.[2] He was kind (was not going to cause her more trouble than necessary) but he also wasn't going to raise another man's child brought about by his almost-wife's (at the time, he thought) infidelity. I think many of us would also reconsider when directed to raise the scion of a deity by a literal angel.

[1] https://biblehub.com/matthew/1-19.htm

[2] https://biblehub.com/matthew/1-24.htm (the interaction was the the verses prior.)