What does "boys will be boys" mean?

One can expect boys to act childishly or misbehave, as in We told the kids not to eat in the living room, but when we got home there was a big mess there—oh well, boys will be boys. This term came from a Latin proverb, translated as “Children [boys] are children [boys] and do childish things.” In English it was first recorded in 1589.