Earlier quoted context omitted.
Does it really matter whose child it is? You seem to be writing this as if she might give birth to a goblin or something like that. I can't see what's "speaking practically" and "putting the morality aside" here, because there's not really any practical difference.
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 rea…
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.)