That being said, don’t dust off your family tree just yet - remember I said there were ugly details? Things Get Hairyįor the most part the idea of a single brown/blond gene matches how hair colors are really passed down. No matter which genes they pass down, their kid should end up blond.

Since they’re both blond, they must each have two blond t-shirts and no brunette jacket. With this analogy, you can also see how two blond parents should never have a brown-haired child. They were secretly wearing blond shirts under their brunette jackets, and when it came time for each of them to pass down one item of clothing to their kid, they both gave the shirt! This is what both of our brown-haired parents had going on. Having one of each will leave your hair brown, even though you’ll secretly be carrying the blond allele in every cell of your body.

Since you have two copies of each gene, that means the only way to have a recessive feature like blond hair is for both of them to be the recessive allele. In the same way, features created by recessive alleles only show up if there isn’t a dominant allele around. If you wear one of each, only the jacket will be visible. You can think of recessive alleles as t-shirts, and dominant ones as jackets. If two brunette parents have a blond child, they had to have instructions for making blond hair hidden in their DNA. The blond allele is recessive, and gets covered up. That means that even if only one of your two alleles is for brown hair, your hair will be brown. It turns out that brown hair is dominant. What happens if you got a ‘brown’ allele from your mother, and a ‘blond’ one from your father? Brown allele, brown hair.īut there’s a catch - you have two copies of each of your genes. Seems simple enough, right? You have the blond allele, you have blond hair. Let’s pretend that there’s just one gene that controls hair color, with a ‘brown’ and a ‘blond’ allele. And your genes can come in different versions, called alleles. You probably know that DNA is organized into small pieces called genes, which help control how our bodies are built. How could blond-making DNA be hiding in every cell of a brunette person’s body without them growing any blond hair? The answer lies in understanding ‘dominant’ and ‘recessive’ features. If two brunette parents have a blond child, that means they had to have instructions for making blond hair hidden in their DNA.

I’ll give you a mostly-true answer first, and then dive into the ugly details if you’re still with me. The genetics of hair color is still a bit of a mystery, but we do know a few things.

Abbreviation for hair color