What Causes Curly Hair in Humans?

Curly hair is the result of genetics, just as is every other feature that you inherit. The structure of curly hair is different from straight hair, and that's why you end up with curls.

Memory Material

The shaft of curly hair, which is different from the shaft of straight hair, is the result of asymmetric differentiation of the precortex part of the brain, meaning that hair fiber is a "shape memory" material.

Oval Follicles

If you look like Orphan Annie, this means that your hair follicles are oval. If they were round, your hair would be straight.

Ribbon-like

Ribbon-like yet flat hair follicles will produce tightly coiled hair. Hair follicles are the tiny pockets in our scalp from which hair grows.

Genetics

Our genetics play a huge role in determining what kind of hair will we have. Two curly-haired people will most likely produce a curly-haired baby. Even if just one of your parents is curly-haired, the odds are good that you will inherit curls because curly hair is a dominate characteristic.

Size and Quantity

Curly hair can be thick or thin. This is determined by the size and quantity of your follicles: large hair follicles will produce thick hair, whereas small follicles will produce thin, curly hair.

References

• Understanding Genetics