Because Michelle can't take care of all 19 children on her own, she has implemented the highly controversial "buddy system" where older siblings take care of younger ones. The oldest daughters have been taking care of young children for most of their lives. And then, once they get married off, they're expected to continue taking care of babies without a break. In the end, the young women never get a chance to have a "normal" childhood or even get to experience their adolescence, which is an important milestone in human development. If anything, they're simply expected to become empty clones of Michelle. Tragic.