I am trying to find what the percentage or even general odds of a baby being born with a cleft chin, whose parents don't have cleft chins, and whose grandparents didn't have cleft chins. From what I've read, virtually any mutation is possible with or without the genetic history. So, I'm not asking if it's possible, but apart from terms like "rare" or "uncommon", is there any data or calculation that can suggest just how rare it is? From what I've perused, it is suggested that it is more common for a mother or father with a cleft chin to birth a child without one than the opposite. Any thoughts on any of this?