You Can't Take It With You came out thirty years before the official film rating system was introduced in 1968. But if it had been rated, it would almost certainly have gotten an all-ages seal of approval.
There is no cursing, no blood, no gore, and no sex (just a bit of chaste kissing and hugging.) The Vanderhof family is a bunch of artsy hippies, but they're not the free love, drug-using kind of hippies. They're about as edgy as a bunny toy.