I consider "political correctness" to be the sort of back-bending linguistic contortionism typical of politicians and PR departments terrified of offending anyone. That's not what's going on here. I'm gay, and while I don't have children, the idea that, were I to adopt one, I'd risk sexually damaging said child with my gayness is offensive. Can you imagine the reaction there would be to someone asking a parallel question about race ("Does the white child adopted by black parents have problems with his racial identity?").
There is nothing wrong with the question you asked. Absolutely nothing. We are intelligent, educated people - if we ask these questions, it's not because we want to ridicule people or offend them,but because we are genuinely curious. The other option would be to remain ignorant and not ask in the fear that this question might offend someone, which in my brain is just sick and wrong.
But these are not randomly selected questions. To illustrate, consider if someone posted a story asking whether Jews were genetically disposed to be greedy. This could be dressed up quite a bit, and it's not impossible that this would very rarely be asked by someone without any social awareness. But there's a smart prior which says that someone asking such a question has a strong agenda and that the "just asking questions" bit is a smoke screen.
It's not the question that's wrong, but what you do with the answer that's important.
It's like asking - is it true that black people have statistically larger lips than people of other colours - then is that really racist? I don't think it is.
But if you take the answer to that question,and somehow infer from it that because of it your "race" is better than others, then it only means that you are racist,not the question.
My point is - scientists need different kind of statistics to understand how the world works. If they ask if a child raised by two gay people is more likely to have problems with its own sexuality, then I don't see that as homophobic or aggressive - it's not personal after all.
Racial social identity in inter-racial families is a hugely important issue, and ignoring it is deeply harmful to a child, who faces harassment from peers and strangers, internal confusion, etc.
I consider your hypothetical question to be a legitimate one.
The problem is that these sorts of questions are often the precursor to banning unconventional families until someone proves that no harm is done. That sort of thinking is harmful, but I don't think asking the questions is harmful.
I agree that there are potentially-interesting sociological questions to be asked, but it's possible to ask them in a way that's not loaded. The parent poster asks about whether the kid has "problems with his sexuality," which I take to be asking either whether as a result of having gay parents, the kid is gay (implying that gayness is a "problem"), or alternatively, whether the gay parents have caused some problem other than gayness... like what, one wonders? Is the implication that being around gay people makes one asexual, or that gay people abuse children such that they grow up sexually stunted, or something? I have difficulty envisioning an implication that isn't based on an underlying assumption that gayness is bad. Had the poster instead asked, "did having gay parents make the child gay?", that question would have ended up in the "good-natured but misguided" category, and I would have felt more comfortable just answering the question instead of complaining about it.
Likewise with the race question: if a poster had asked "does the white child raised by black parents identify more strongly with black culture than other white children?" that might be a legitimate sociological question, but the implication that that's a problem is what makes the question problematic.
I believe it will be more offensive if I don't ask any question and I will just keep my opinion.
Honestly most of the people in this planet believes that there is something wrong in gay marriage and gay adopting kids, (there are more country where gay don't have the right they deserve, than country where they do have rights) investigation, and asking question -I believe- is the only way to change things.
I am sorry if you felt offended by my question, but you should realized that in some country (mine as example) being gay, gay marriage, gay adopting kids, are big issues, and there is a lot of questioning and discussion about.