Preston's wife - one thing I've never understood
Preston had a wife, and, when you decide to get married, it's usually based on love.
The same with their kids; to have sex, then it's usually also based on attraction.
So unless they just decided to get married, only for the sake of being married, and Preston masturbated in a cup (which would require being horny as well), to make/give his wife artificial insemination, then the grounds the movie is based on, is ruined there already.
All these voices in my head, and not a single one I understand.