system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why Does curly hair stay curly?

I understand *why* people have curly hair, but why/how does it go back to being curly after using a straight iron, or after being pulled straight in a ponytail all day?
gpt
There are actually a lot of different things that factor into making your hair curly. If i remember right the amount of Sulfur-Sulfur bonds or "disulfide" bonds. These are from the tertiary structure of the protein in your hair. The more disulfide bonds your hair naturally has, the more curly.