For me it was always Hormones or when I stopped caring for hair and took the following steps:-
Stopped oiling for 1 year ( even though I had an oily scalp, my hair kind of became rough).
Lack of self-awareness for taking care of hair.
My current apartments provide 60% filtered water, so the rest harmful chemical combinations made my hair rough. ( I used to have silky hair before I moved to my new apartments because the previous one provided 100% filtered water).
Stereotypes not to let teens take care of themselves lol, else they'll become bad.