We're talking sheboons here, odds are she has no idea about that.Daughter can claim (to the doctor) that she signed 'under duress', revoking the consent. One private cell phone call and the doctor can legally lie to the father every time.
Also, treating the son different is horseshit. No degeneracy applies across the entire family. Period.
Applying it only to his females means he wants the daughter as a backup.