Magical ability could be explained by a single autosomal dominant gene if it is caused by an expansion of trinucleotide repeats with non-Mendelian ratios of inheritance. - Andrea
Biology major Andrea admits she was not a biology major yet when she read the Harry Potter books. So it is only recently that she’s come across J.K. Rowling‘s statement that the wizarding gene is dominant (that is, it’s much more likely to be passed from parent to child, and much less likely to be present in the genome unexpressed). Andrea also noticed the confusion surrounding Rowling’s statement, with a lot of folks seeming to think that the author had gotten one of the basic foundations of genetics wrong. If the wizarding gene was dominant, how could you explain muggle-borns, wizards born to non-wizard parents? And how to explain squibs, the rare non-magical offspring of wizard parents?
Andrea wants Rowling to know that she’s got her back, and sent her a six page scientific paper supporting her claim. Fortunately, she also shared it with the internet. And while I would be the first to admit that I don’t remember much from AP Biology and have a childish enjoyment of the simplicity of the Punnet square, I believe this is the crux of her argument: