You can’t claim you have watched any anime unless you have seen the  ahoge (アホ毛) in action. The ahoge, of course, is the conspicuous lock of hair that protrudes from a character’s head. It can be from the bangs area or the top of the head. It’s usually depicted as a single hair but sometimes it can be inferred as a lock. Ahoge come in all shapes and sizes, and I’m sure you’ve seen them all. It’s not considered a hairstyle, more of a bodily trait that cannot be created artificially in the anime world. As with everything else in anime, the invention of the ahoge can be traced back to Dr. Tezuka Osamu, but that’s enough Wikipedia for now. Let’s talk science.

Since the ahoge is a physical trait that cannot be artificially created, we can assume that the presence of an ahoge represents a genetic phenotype. Well, no we can’t but let’s just entertain ourselves here. In order for geneticists to piece together how a trait is inherited they have looks at statistics from thousands of specimens, observations, and breeding trials over several years. I have around 2 hours, and Danbooru.

The genetics of ahoge are as hard to study as the Genetics of the Subconcious *receives fistbump from Touhou fans* for two main reasons. The first is that they are totally fucking made up, but let’s ignore that for now. The second is that there are very few samples to study. By very few I mean like two.

To be a meaningful subject of study, we need to find someone who not only has an ahoge but a family. You’d think this is simple but you would be surprised. The best reference here is Clannad, which is great because the family tree is full of people with ahoge and it goes multiple generations. After a long time of hardcore simulations and research (read: around 2 seconds of guessing), I have come up with the conclusion that the presence of an ahoge is a simple recessive trait.

See that Punnet Square? It means that I mean business.

One uncertain thing here is Tomoya. In some scenes he’s drawn with what seems like a partial ahoge or something resembling such. Thus it’s quite possible that Tomoya is a specimen of incomplete dominance, and that the A allele of “no ahoge” is incompletely dominant over a. It’s also possible that ahoges are based upon interactions between multiple difference genotypes and several gene loci (called epistasis), making the above chart totally wrong and this whole topic really really complicated. Also notice that Nagisa and Akio have two ahoge (which is rather uncommon) and that Sanae has three (almost unheard of). This could imply that there could be multiple ahoge alleles and even co-dominance. If that were the case, then it could mean that the a allele is extremely prevalent in the Furukawa family, but Ushio’s lack of an ahoge would be difficult to explain in a co-dominant or semi-dominant model.

Occam’s Razor, which is about as dangerous as sprinting while drunk with rusty scissors in the venerable world of “guessing random shit from totally insufficient evidence” would thus have us believe that not having an ahoge is simply and completely dominant over having an ahoge, and thus only the genotype aa would create a phenotype with an ahoge.

As shown by this totally in-depth, exhaustive diagram, our theory works.

Not convinced yet? Well, I would love to do a formal study but that means I have to have a science grant, and all kinds of other resources. But when I do get that grant, you can bet I’ll be running those test crosses with fervor. I don’t have an ahoge, after all.