Haha! Alright...the REAL answer, as far as I know, is one of 3 things
(1) The two parents heads have a blonde somewhere between them on the image chart. (If you don't get it I'll explain)
(2) They had a child outside of their radius which would be considered a rare child (which is what I think it is, so congrats!)
(3) Or she is having an affair with another man LOL JK! hehe the husband may want to see a lawyer