I said unwise, not impossible, and I chose the word with care. 10% matters enormously if you are trying to squeeze a human baby's head through it while doing as little damage as possible. The engineering of the human female pelvis is a very unfortunate compromise between running and childbirth, and tolerances are... tight.

Living arrangements have bewildering diversity across cultures, there is no 100% on anything, but I'm on safe ground when I say the overwhelming majority of extant cultures that practice early female marriage also overwhelmingly practice both both patrilocalism and multigenerational households.