Anyone who has sat through a high school biology lecture on genetics understands the basics of dominant and recessive alleles, which explain, among other things, how two brown-eyed parents can have a blue-eyed baby.
When you start talking magical ability, however, things become more complicated.
That was the topic of one panel at Future Con, a convention "where science meets science fiction," held this past weekend. In "Harry Potter and the Genetics of Wizarding," Duke University professor Eric Spana discussed the intricacies of wizard DNA.
Fans of "Harry Potter" know that, while two magical parents will likely have magical children, that's not always the case. Occasionally, an all-magic union will result in a squib, or non-magic, child (think of poor Argus Filch, tasked with cleaning all of Hogwarts without so much as a wand to help him out). On the flip side, Hermione Granger — one of the finest witches of all time, IMO — was born to two muggle parents. Throughout the series, we learn that students like Seamus Finnigan had one magical and one muggle parent. So how the heck is magical ability passed on?
According to a summary of the panel from Live Science, Spana debated whether magical ability was a recessive trait (much like the Weasley family's red hair), meaning it's possible for an individual to carry the gene and potentially pass that gene onto offspring without expressing its traits. He ultimately decided it wasn't, though — thanks to one Rubeus Hagrid.
You see, Hagrid was born to a giant mother and a wizard father. This meant Hagrid was born a wizard with only one copy of wizarding DNA in his blood (giants are non-magical). Thus, Spana concluded, magical ability must be a dominant trait.
If that's the case, how did Spana explain children like Hermione, who are the first in her family line with magical powers? A good, old-fashioned genetic mutation, possibly occurring in a sperm or egg cell, or after the egg is fertilized. (Yeah, don't you wish you'd remembered more from AP Biology now?) As for squibs, Spana posited that parents could carry a mutation of the wizarding gene and pass it on to their child.
Science, man. It's pretty magical.
From June 1 to 30, HuffPost is celebrating the 20th anniversary of the very first "Harry Potter" book by reminiscing about all things Hogwarts. Accio childhood memories.