To be fair, OP didn't say that either role should always be fulfilled by any particular gender, just that it's good to have a mix in a family. In fact, he didn

To be fair, OP didn't say that either role should always be fulfilled by any particular gender, just that it's good to have a mix in a family. In fact, he didn't mention gender at all, so it could also apply to families where the partners are homosexual.