I have been wondering a great deal of thinking about Metamorphagi lately, and I have a good idea of just how rare they are. But I do have other ponderings on the topic.

We seem to have a good understanding of the genetic components of a Muggle-born wizard, but now I wonder about the genetic components of a Metamorphagus. We know that a Metamorphai doesn't need to be a pureblood witch or wizard, but can a witch or wizard with a Muggle parent possibly be a Metamorphagus?

Someone who has done a great deal of study in genetics would be really helpful. I assume the gene for the abilities of a Metamorphagus are either recessive or carrier. Do you think the fact that Tonks herself is a Metamorphagus increased the chances of Teddy being born with the ability? Does anyone know of any genetic illnesses I could study that you think would be at all similar to this ability?