Hair here and everywhere. Help!

It's bothering me that whenever I clean the floor I there's so much hair especially in the bathroom and it's my hair. Long black hair. I have a think hair so, even if I shed a lot, I don't notice it thinning. It remains thick. I wonder what causes my hair to keep falling. Aside from the shedding, I have early developement of gray hair. I have had a few already when I was in highschool. And now, I have a lot. My siblings and relatives noticed it when I went back home months ago. Now, that I have lots of white hair I am thinking of dying it. I have read that stress could cause white hair. Still some people don't have a lot even if they are being stressed more than I do. Heredity? My mother did have white hair at an early age.They also say that sleeping with wet hair can cause it. Or tying it in a pony tail while wet cause white hair. I haven't read any scientific evidence as to what the causes are. Any thoughts? And what to do to avoid having white hair. Maybe I can still save the rest of my black hair.