Hair question?

hey guys, im jus curious, wen ur 8 yrs old, is ur ALL ur hair grown out, like, u know as you age more hair grows from like 1 years old to 5 yrs old your hair grows in ....but at 8 yrs old, is like ALL ur adult hair grown or is there still some to grow? Plz no stupid answers...i heard ppl have the same amount of hair follicles as they did when they were born, but the thing is, as they grow older, the hair grows in to be thicker, sois at 8 yrs old all ur hair grown out?