Why Do Some People Have Curly Hair and Others Have Straight Hair?

Your hair’s shape depends on a special protein called keratin. If the keratin is round, your hair will be straight. If it’s oval or flat, your hair will curl or wave like a coiled spring. It's all about how the hair grows out from your head!

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Examples

Your mom might have curly hair because her keratin layers are oval-shaped, just like a donut.
Your brother has straight hair because his keratin is round like a marble.
Your dog’s fur is wavy because it has a mix of oval and round keratin shapes.

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Categories: Biology · Hair,Genetics,Proteins