BoM/TWS Message Forum

That probably depends if the DNA left behind checks as their own or that of the impersonated character. (And, judging by "Kipper's" response, it's the latter, as they've used it to frame people.)

That said, the issue of fertility being disabled while under a mask (other than capturing the imago of someone already pregnant) is part of the mask disabling it. The masks leave no DNA residue because those components contain no connection to the wearer's essentia and therefore dissipate when they lose contact with the wearer, which includes newborns. Technically, if the wearer is impersonating a woman, they *should* be able to become pregnant (provided they're on the right moment), but the mask essentially blocks that (or more specifically, it's handwaved in order to avoid a literal pregnancy scare).

If we're talking about a man impregnating a woman, it's most likely that it depends on the DNA left. I'm assuming that the DNA matches the impersonated individual, the end result would be a pretty exact match, since that counts as DNA (much like saliva and hair do). If we're talking about an agent being impregnated, it's probably they'll run at the same "blocking" mechanic to avoid having to stay 9 months (more or less) out of commission, though.