Curlee Gurlee: Genetics of Curly Hair

Ever wonder about the genetics of curly hair? How did you get your curly hair and where did your curls come from? Scientist Julia Ravey is here to explain!

Your curly hair is a very special gift which has been passed down through your family for generations. Like a top-secret cookie recipe created by your great, great grandmother and shared with each generation, you receive a unique set of instructions from both your parents to make you, you! These instructions live inside the cells of your body and dictate many of your traits from eye colour to height. This code is called your DNA and contains specific instructions for each trait called genes. As your parents both give you a copy of their DNA, you end up with two copies of almost every gene!


Although we all have the same genes, there are small changes in every person’s instructions which make us look different. And these small changes are what determines how curly or straight your hair is. Our hair is so important that we don’t just have one ‘hair’ gene but approximately 12! These genes can either instruct our hair to be curly (C) or straight (S). The DNA given to you from your Mom will contain a mixture of 12 C’s or S’s and so will the DNA from your Dad – leading to about 24 C and S instructions.


But for each gene only one set of instructions can be used, and the way the body decides this is based on which gene is more dominant. Let’s imagine both your great, great grandmothers had slightly different recipes to make chocolate chip cookies which they passed down. One of these recipes might be easier to follow, so these instructions are always used to make chocolate chip cookies. This would be called the ‘dominant’ cookie recipe. A similar process happens with the C’s and S’s passed down from your parents. It is thought the C genes are more dominant but that is not always the case! So a person with straight hair could have some hidden C instructions in their DNA, meaning they could have a curly-haired child.


But even when your body has selected the many S and C instructions to make your hair, that is still a lot of different information! So, how does your body know whether to produce curly or straight hair? It is normally the case that the more C genes you have, the curlier your hair will be whereas the more S genes, the straighter your hair will be. The mixture of these C and S genes leads to the different hair textures, including the 9 types of curly hair.


Your wonderful curls are a beautiful present given to you by your ancestors and are a part of the incredible history of your family. Wear them with pride!

Julia Ravey is studying for her Ph.D. in Neuroscience. You can visit her online on her Instagram, Twitter, and Youtube Channel

Atara Twersky, Author of Curlee Girlee is a TODAY Show Style Icon. Her mission is to teach girls to embrace the beautiful curls they have with power and confidence. Join us as together we change the “coarse” of curly hair. Don’t forget to check out our recent article on What to Do or Say if Your Daughter is Showing Signs of Hating Her Curly Hair.

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