By Nonie Arora
Dr. Spana explains the wizarding gene to eager students. Credit: Arnab Chatterjee
How do recessive alleles and the world of Harry Potter connect? Some students found out last week from Dr. Eric Spana, a faculty member in the Biology department.
He started off by explaining how a mutation in the MC1R (melanocortin 1 receptor) gene causes red hair in humans because of the way it affects a pigment called eumelanin. He added that MC1R is a recessive gene, and showed a pedigree of the Weasley family tree. Professor Spana pointed out that J. K. Rowling had gotten the genetics right. The Weasley clan has red hair and so does Harry’s daughter Lily. This makes sense because Harry must have a recessive allele for red hair since his mother, also Lily, had red hair. Whether this is intentional or just fortuitous casting, who can really say?
He then explained some potential retroactive genetic “crosses” that could be done to determine whether the “wizarding gene” was dominant or recessive. As a quick refresher, recessive alleles require both the mom and dad to pass on the same genetic sequence to the child for the condition to occur, while dominant alleles require only one copy.
According to Professor Spana, Step 1 was to check whether a witch and a muggle who mated ould produce a wizard. Indeed, this is possible, and the evidence is Seamus Finnigan, a half-blood wizard. Due to these results, the gene could still be dominant or recessive.
In Step 2, he explained, you mate a wizard to someone who could not have the wizarding gene. Fridwulfa, the giantess, married Mr. Hagrid, a wizard, to produce our beloved Rubeus Hagrid, who was a wizard. Since giants cannot have the wizarding gene, but Hagrid is still a wizard, the wizarding gene must be dominant!
Crowd of students ask provocative questions about squibs and recessive vs. dominant inheritance. Credit: Arnab Chatterjee
You’ll have to stop by Dr. Spana’s office to ask him more about where muggle-borns and squibs come from. There’s a few different genetic explanations, and I encourage you to do some thinking and exploration.
Outside of his work on the genetics of Harry Potter, Dr. Spana also researches and teaches Genetics & Developmental Biology at Duke.