Why is the youngest always the most spirited, particularly the youngest brother?

I don’t know if parents relax a little more with each child they have, or if they simply become too tired to keep everyone in line, but the youngest boy of a large family is typically a handful of trouble.

Of course, maybe it depends on the individual.

My uncle is the youngest of four – and he is a career M.D.

Louis was one of those reckless kids who spring from large middle-class families, the youngest brother, out of reach, who for parents come as a last piece of busywork at the end of a long semester; a wild kid who everyone says can go either good or bad, but almost always goes bad; a kid on Ritalin; a kid you either want to like but don’t, or want to hate but can’t; a kid who makes some teachers believe in God: If something is this bad, there must be something somewhere just as good.

-Rich Cohen, Tough Jews