
Seeing as how their moms are both best friends and became pregnant at the same time, we can extrapolate that they both agreed to raise both of them together. This confirms that their moms are both promiscuous, and are likely best friends. Their fathers both claim to have scored with two women in their town, and they were both “sluts.” He’s obviously talking about their mothers’. If they aren’t really friends (and also because they’re friggin teenagers) it’s unlikely that they made the decision to live together. In the episode “Choke”, Beavis says, in a a very matter-of-fact tone that Butthead “is not really my friend”. I guess they live with each other because they are best friends, but really? They have a fairly toxic relationship, and they seem to genuinely dislike each other at times. Some theorize that they are related, but I doubt it. This begs the question: why the hell do Beavis and Butthead live with each other anyway? It’s never explained when they met and became friends. They once skipped school for 3 weeks straight, so there’s no way they live in the same home as them.

So okay, we know what their fathers are doing, but that still leaves the question, where are their moms? It’s not just that they are never home because they are always out working or partying. It is often implied that they both have single mothers, but they never just come out and tell you. Throughout the show, it’s never actually explained that they don’t know their dads. In the movie, we meet who are probably their estranged fathers.
