I just brown hair.  I wonder how many people have brown hair.
Quite a lot!  It's actually the second most common hair color.  Second to black hair of course.
Is there a reasons so many people have brown hair?
Well it depends on the level of eumelanin.  If there is more, the hair color will be darker and vice versa.  Brown just happens to be in the middle.
Does the color of the hair change anything else about it?
Well actually the darker a person's hair color is, the more individual hair follicles they have on their scalp as well!
Does that affect the strength of the hair?
No not really.  Hair strength can be maintained though through hair care routines.  Just vary your routine according to the physical characteristics of your hair!