Graying doesn't occur at the same rate in all people. It is caused by a decrease of cells that produce melanin, a pigment that gives color to hair. Graying begins at the temples and extends upward to the top of the scalp. Not all seniors have gray hair. About 35 percent don't grey until they are very old.
Pattern baldness is genetically determined and occurs in young men.
Baldness later in life is not genetically determined. Both men and women lose scalp hair later in life. As we age, fewer hairs grow, fine hair increases and coarse hair decreases. Hair diameter, density and breaking strength decrease. When the human body comes in contact with electricity, current passes through it, causing shock.