I don't play challenges, so I wasn't sure. Seems rather a sexist rule to me!
there's a handicap you can take, for bonus points, where the heir has to be either a male (patriarchy) or female (matriarchy), and then with OFB you have a category for the "family business" which is passed down from founder to heirs, thus, if you have the handicap it has to be passed down the right side of the family