why hair white

Those of you who have followed my obsession with my hair coming back will be happy to hear it is growing in (YEA!). So far I have peach fuzz, but I can tell there is more covering my head. My question to you is: why is the hair white, and does it stay this way? A few little hairs on one temple are dark, but the rest of it seems to be white. This doesn't upset me that much because I figure I can always dye it later, but am just curious if anyone knows why, and if later on the hair comes back its natural color. By the way, think of me on Sept. 18 when I will have a second, preventive mastectomy on my right breast (I had cancer in the left one and had the mastectomy; now, after finding out I am BRCA 1) I will have the other breast removed. Thanks! Ohilly