My highschool used to do blood typing as a science experiment in bio. Part of the homework was to find out what blood type your parents were. One girl went home

My highschool used to do blood typing as a science experiment in bio. Part of the homework was to find out what blood type your parents were. One girl went home (before I was there, the teacher shared the story during the genetics unit), asked her parents their blood types, and "Dad, that's not possible. You can't be that blood type." One lawsuit from mom later, and the school doesn't do that lab any more.