i don't know. the greying and whiting of hair is usually genetically determined so blame it on your parents or grand-parents. my head hair turned grey in my 30's and by my mid-40's i was as white as snow. if you don't like grey pubic hair shave it off. or dye it a different color. or just ignore it as part of our progressive aging cycle.
why do i have gray pubic hair at the age of 43