(oh no i’m so sorry i’m answering this so late)
it’s more magical!
the actual cause isn’t known in-universe, wrt it being some kind of scientific virus or a magical curse, but i like to see it as more of a magical/curse based problem. but a child born to two werewolves wouldn’t be a werewolf. they’d have to be bitten. but, given the aggressive nature of weres, and the fact that they like to bite pretty indiscriminately, it’s not unlikely that someone who’s around two werewolves isn’t going to get bitten.
still taking questions about were!