We have Le$bian friends with children. They always get "which one of you is her/his REAL mother?" By this the questioners mean "biological mother," and this is horrible, rude, and shows a prurient interest in the sex lives of others. I mean, what concern of the asker's could it possibly BE? And what on earth possible difference could it make?
One friend has come perilously close to saying, "So, you want to know which of us had sex with a man?"
Complete silence, with "I beg your pardon?", and lifted brows if they persist, and apparently they do, is a more polite response, but the utter nerve of people who would ask such a question -- well, it really peeves me, too.
Their usual answer is "both of us," which lets the prurient interest and generally nasty nosiness become clear as the questioners continue to insert more and more rude, smelly feet into their mouths.