What Makes Hair Curly?
The curliness or straightness of hair depends on the shape of the hair follicles. These are tiny openings in the skin through which hair grows. Different people have different shaped follicles.
As hair grows, the hair shafts come through the follicles round or flat. If the follicles are round, the hair will grow out straight. If they are shaped like little ovals, the hair will grow out curly. The flatter the hair shaft, the curlier the hair.
Curly hair grows unevenly, and some parts of it grow faster than others. This causes the hair to “twist” and curl.
A curly hair can also be described according to its composition and structure. Even if you’re born with round follicles, there are some ways in which straight hair can turn curly.
Scientists have found that a cellular receptor called EGFR clusters on the outer root sheath of a follicle and appears to regulate the growth of hair. Certain cancer drugs that inhibit these receptors may cause a patient to develop curly hair as a side effect.