I think everyone is different. I see plenty of people over 50 with very thick hair. My dermatologist says it’s mainly genetics. Your mother’s hair condition often predicts what you will have as you age.

Of course, vitamin deficiencies can cause shedding (I did have vitamin B12 deficiency in April of 2023). I got shots and got it back up, but maybe, that contributed to mine. Idk. But, the rapid weight loss came right after that too. Plus, post covid syndrome. I got that in Sept 2023. Within days I saw huge hair loss. You can find photos of hair loss from covid online. There are other causes too like hormonal and autoimmune related. Sometimes, no cause can be determined.