Research finds HP descended from wizards

"Harry Potter and the Deathly Hallows provides a lot of valuable information about magical families that strongly suggests a role for genetic factors.

"For example, magic exists in at least seven generations of the Black family and at least three generations in others. We also see twins – the Patil and Weasley twins – with the same magical abilities."

The article details their findings, which, in part, contradict a previous study of wizard genes which 'claimed magical abilities depend on a recessive version of a gene: all wizards and witches thus have two copies of the wizard "W" gene, distinguishing it from the ordinary M, or Muggle, version.' TLC referenced this study here in 2005. Todays new Oxford-based study, however, builds upon the formers findings and says (with mildly spoilerific details in tow):

Rather than being all down to one gene, they believe enchanted skills can vary across a spectrum of strength, depending on the combined influence of a dominant gene for magic, which is turned on or off depending on epigenetic effects, and modified by the influence of a number of genes, along with the environment.

There appear to be three magical skills that are conferred by specific genes. "One of these is the capability to speak to snakes (parseltongue), known to be only a feature of those who are direct descendants of Slytherin.

Another is to be a seer; Sybill Trelawney, although not perfect, has this ability, and her great-great-grandmother was also extremely gifted in this respect.

Lastly, being a metamorphmagus (the ability to change one's physical appearance) is an ability that Nymphadora Tonks passed on to her son," says the BMJ paper.

While this hypothesis may only be based on the fictional world of author J. K. Rowling's creation, the researchers still wait for a full analysis of a wizard's genetic code in the future, and conclude: "magic shows strong evidence of heritability."