Ihateregistering1 said:
Even though the OP did a not particularly good job of wording what they were asking about, I do think this brings up two interesting ideas and questions.
Ok, let's say that they did have a way that a pregnant woman could get an injection and it would 100% guarantee that her kids would not be gay or trans, should she be ALLOWED to get it (note that I didn't say 'forced' or 'required')? I'm sure some people would say that such a procedure shouldn't be allowed at all, but to me, that begs the question: if we let a woman terminate her fetus on the basis of "it's her body so it's her choice", why would that same concept not apply here? If we let the pregnant woman decide whether the fetus lives or dies, how is that so much better than deciding what its sexuality will be?
2nd question, let's say that, instead of being injected into a pregnant woman, they actually did have an injection/procedure/whatever that would literally turn a gay person straight, or a trans person cis (or whatever the term is). Not "psychological reprogramming" or anything like that, but literally something that alters your genes (obviously this is sci-fi, but humor me), should people have the right to get it done if they choose to do so?
I think these are better thought questions than in the original OP but I'd still say no to both.
With the first question there is a big difference between pro-choice and what you suggested. Parents do not own their children; pro-choice is based on the fact that women own their wombs and can choose to not have a fetus growing in it. They don't have the right to do anything to the fetus which will grow into a child later. The difference is basically that pregnancy is a big ask to a woman and (since the child doesn't exist yet) they have the right to refuse to do it.
There is no difference (for the pregnant woman) between being pregnant with a gay kid or a straight kid so the pro-choice justification doesn't hold. The difference comes when the child is born and grown. The parents are carers of their children, their decisions in this stage are for the benefit of the child not themselves or their own prejudices.
It's a "designer baby" issue which some people are against across the board. I'm not, but screening (or whatever tactic you use) for genetic syndromes and diseases is very different to choosing specific characteristics like blue eyes etc.
The second one probably wouldn't be possible to make illegal but I would definitely argue against it. I'd view it the same way as Michael Jackson's plastic surgery. I couldn't legally stop it but I'd definitely consider it a bad thing. I suppose the time to make it illegal would be at the technological development stage, making it illegal for a group to develop that technology in the first place.
Another thing that's important is that it will almost certainly not be as simple as you have described. I know it was a hypothetical or your part but if we have a borderline maybe-it-would-be-ok for an idealised scenario then complications in reality may push it into not-worth-it territory.