An old wives’ tale says that eating bread crusts is a surefire way of making your hair grow curly. Have you tried it? Unfortunately, it’s much more complicated than that. In fact, a number of different theories still cloud around the formation of curly or wavy hair, and the truth may lie in a combination of factors.

When you look at hair under a microscope at high magnification, it’s clear that there is a very visible difference between hair types. For example, Asian hair, which is almost always straight, has a regular circular cross-section, whereas hair of African descent, which is almost always curly, has an oval, kidney shape.

So the cross-sectional shape of the hair fiber seems to play a key role, but what actually determines the shape of the hair in the first place?

To understand this, we need to look at the way in which the hair forms within the follicle from its individual cellular building blocks. Some evidence leads scientists to believe that differences in the protein composition of the cells within the hair could be the fundamental cause of differences in curl.

Whatever the cause, like most of the properties of your hair, there is certainly some sort of genetic component. So if you don’t like your curly locks or wish your hair wasn’t so straight … then blame your parents!

Photo Credit: @iStockphoto.com/SavchenkoJulia