Playing devil's advocate: Shouldn't those who are not in a marginalized group be somewhat expected to have a modicum of understanding for those around them, though? No one should be expected to explain how, or why, they are who they are, and being pointedly asked about it generally puts a contentious focus on that aspect. Many, many people have put their energy and effort to explain all sorts of aspects about themselves, which are readily available at a moments notice. Why not rely on those instead of bringing up a potentially vulnerable topic and/or using a single aspect of one's identity as a talking point?