I have a mosaic of hair types on my head. I have furry hair on the left side of my head. On the right side, the hair is full of loose and medium-loose ringlets. The very front of my hair, where bangs would be, is wavy, almost straight, as is the hair around my ears on both sides of my head.
The hair on the back of my head is 100% bushy and kinky, except for the areas that extend from the sides. Those areas are 1) furry on the left and 2) wavy/curly on the right. A pronounced region of African bush separates the two.
The hair at my nape is wavy fur.
The question is why? What, developmentally, causes such a pattern? It can’t be solely genetic, since the hair follicles all the carry the same genes. They’re obviously expressing those genes differently, but how?
Or am I wrong in assuming that all the hair follicles on the head carry the same genes? Hair texture, as far as I know, is not a sex-linked trait. But couldn’t some of the hair texture phenotype be influenced by genes on the X-chromosome? Is my hair a mosaic because I’ve got the whole “calico cat” thing going on? My parents do have striking differences in hair texure. My father has fine, wavy hair. My mother has “straight from the Motherland” hair. (Both are black Americans, btw).
I’m sure my hypothesis is wrong, but I can’t think of any alternatives. Can anyone drop some Doper knowledge on me?
This is one of those things that’s going to be impossible to answer, not least of which because the genetics of hair texture, like most things, isn’t well understood.
First off is the mundane. People have different hair textures normally. Not only that but it changes throughout their lives. It’s not all that uncommon for people to have wavy or even curly hair as children that straightens out with age, and I know of at least one case where straight hair went wavy with age. It’s also not uncommon for men to have sideburns that blend into wavy hair and then straight hair. So the fact that your hair comes in a few different textures may be completely meaningless.
Next the unusual. I’m assuming you are female, and if so you may be experiencing the effect of female mosaicism. I have no idea if hair texture is influenced by the X chromosome, but since hair we know that hair colour, thickness and growth are all influenced by the Y chromosome it hardly seems implausible.
And finally the outright bizarre. You may be a chimaera. A lot of people are. In essence a person is formed form the fusion of two non-identical twins. As a result the body is composed of a patchwork of cells form each sister genotype. I’m not sure what the scale is for chimaera mosaics, but since most of what you describe seems to be a left-right difference it’s plausible.
Since Blake has already covered most of the points I would have mentioned, I’ll just offer this link on human hair texture, which also mentions that the genetics is not well known.
