From what I can tell zero was basically the result of a one night stand - who knows, it might have been a coupla nights - but didn’t seem like Sr. would have even wanted Stanley in Kenya for the birth since he didn’t even want the kid, or her, in the first place.
That’s about the size of it. Apparently, Stanley Ann was a royal PITA. Except for sex, no one wanted her around. Including her parents.