Why Hair Curls: Science Offers an Explanation

For those who frequently wonder why their hair is curly and not straight, or vice versa, science has provided a reassuring answer. The shape of a person's hair, whether it is straight, wavy, or curly, is determined by the shape of the hair follicle. The hair follicle is the tiny pore in the skin from which hair grows. If the hair follicle is symmetrical and round, the hair that grows from it will be straight. However, if the hair follicle is asymmetrical and oval or flattened, the hair will grow out curly or wavy. This asymmetry causes the hair shaft to grow unevenly, leading to the characteristic curl. The distribution of keratin, the protein that makes up hair, also plays a role. In curly hair, keratin is distributed unevenly within the hair shaft, with more keratin on one side than the other. This uneven distribution contributes to the bending and curling of the hair. Genetics are the primary factor determining the shape of hair follicles and thus hair texture. Specific genes influence the development and shape of these follicles during fetal development. Therefore, the tendency for hair to be straight or curly is largely inherited from one's parents. While environmental factors and hair care practices can affect the appearance and condition of hair, the fundamental structure of the hair follicle and the resulting curl pattern are genetically predetermined.