Akademik

Дети есть дети
Children behave in a childish way, and they cannot be expected to act like grown up people
Cf: Boys will be boys (Am., Br.). Children will be children (Am.). Girls will be girls (Am.). God's lambs will play (Br.). Young colts will canter (Br.)

Русско-английский словарь пословиц и поговорок. . 2013.