Half sibling (or uncle/aunt) inbreeding is considerably higher risk than first cousin interbreeding. Only sibling is worse.

I have 2 recessive things that I know I carry, thanks to genetic screening. If I boinked a half sibling, they'd probably be a carrier of 1 of them, and there's a 50-50 chance any resultant offspring would have the conditions.

(Neither would be fatal but both would be severe chronic things-- e.g. hemachromatosis.

There's probably other rarer recessive things that I'm a carrier of and don't even know about.

> I have 2 recessive things that I know I carry, thanks to genetic screening. If I boinked a half sibling

...you could take steps to assure safety first, thanks to genetic screening.

Sure, but A) genetic screening only knows about the common issues, and B) if you marry someone random and don't realize they're a half sibling, you might not bother with genetic screening.

It doesn't change the argument. The fact that the father does not know who his offspring are (and the other way around) is quite bizarre to say the least.

Bizarre is sending messages across hundreds of miles using electrified sand. Men impregnating women and moving on is as old as large scale war, at least.

We're not in a large scale war. Today, this behavior is seen as desirable, without realizing what the effects are.

It's selfish behavior on both the donor and the recipient, and who ends up paying for it are the offspring and most likely society as well.

> We're not in a large scale war.

No, but we're in a large society where men can and do have sex with women (consensually or not) once and leave them pregnant. I'm not making a moral judgement, I'm saying that mostly anonymous sperm donations have been happening long before IVF and sperm banks were a thing, so the results aren't as unpredictable as you paint them.

So let's just enable this behavior even more, on an even larger scale? What you described happens, but it's not comparable to this. A single man's sperm can now be used to impregnate several women with a much lower barrier (as we can see from the article posted here). This issue has also been reported elsewhere, it's clearly becoming more wide spread, and we don't know what we're getting ourselves into, all because of greed and selfishness.

The probability of harm to potential offspring does in fact change the moral argument (which seems to be what you were going for).

Hypothetically, even if it didn't harm the offspring, it must be kept track of who are their real parents.