The magic of genetics

Britney Jones
23 January 2012

Harry Potter faces VoldemortEver wondered how Harry Potter was lucky enough to be born with magical powers? It may be as simple as classical genetics.

Genetics explain how your parents passed on some of their own traits to you. For example, you might be tall like your father, or have freckles like your mother. You’ll notice that you aren’t a carbon copy of either of your parents but instead have “parts” of each. In some cases, the pattern of inheritance is unclear and may have more to do with environment. Sometimes, it’s obvious: if one of your parents has blue eyes and the other brown; you likely have brown eyes as the “brown” gene is dominant over the recessive “blue” gene. This is an example of a monogenic trait – a characteristic dictated by a single gene.

Magical ability appears to be inherited in the same way as many other monogenic traits, and the birth of a wizard from two muggle parents (i.e. Hermione) suggests the magic gene is recessive (like blue eyes), which could help to explain why wizards are so rare.

Did You Know?
The existence of squibs like Filch could be explained by a mutation in the magic gene that caused it to be defective (although a paternity test might be in order).

If magical ability is, in fact, inherited, there must be two versions of the “magic gene” – M, which is non-magical, and m, which is magic. Each child receives two copies, or alleles, of this gene (one from each parent). Unfortunately, one copy of the magic gene (m) isn’t enough; you need two (mm) to become a wizard. Therefore wizards may come about in three ways: either both parents are homozygous for the wizard gene (meaning each parent is mm, like Ron Weasley’s parents) or both parents are heterozygous muggles (Mm - each carrying one copy of the wizard gene, as in Hermione’s case), or one parent is homozygous recessive (mm) and the other is heterozygous (Mm) giving rise to a ‘half-blood’ such as Seamus or even Voldemort himself.

Did You Know?
Genes are not carried in the blood, but are found in chromosomes in the nuclei of cells. Blood cells actually lack nuclei; making “pure-blood” a misnomer.

Learn More!


Craig, J. Dow, R., and Aitken M. 2005. Harry Potter and the Recessive Allele. Nature. Vol 436: 776. Dodd, A., Hotta, C., and Gardner, M. Harry Potter and the Prisoner of Presumptions. Nature. Vol 437, p 318.

Article first published December 21, 2010.

Photo Credit:Warner Brothers

Britney Jones

Britney earned her undergraduate degree at the University of Calgary, majoring in biological sciences and minoring in psychology. She then went on to receive a Master’s degree in Biomedical Technology, where she developed a keen interest in health advocacy research. Britney spent two years as a member of the Clinical Research team at the Tom Baker Cancer Centre. Currently, she is in her third year of medical school. 

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