Board Thread:Warhammer 40k General Discussion/@comment-5781149-20130130013422/@comment-3258762-20130317213111

They take in any child in the Schola, but only infants are taken in to be Commissars

On rare occassions, a General may deposit his/her child in the Schola before they die, and then they are raised in the Schola until the General dies. If so, then they can be Commissars, but not otherwise.