those ppl ask just because too many twins nowadays which not made by natural, i think they just corious to ask, not impolite.
Doctor ask as they need to keep record, you know artifical risk is higher than natual, so that make sense that they need to know.
Agreed that no matters natual or artifical, twin mom should all be happy as this a also a gift from god. I am carrying twins too, wk 22 already, waiting their coming...