<P> A widow's peak is a V - shaped point in the hairline in the center of the forehead . Hair growth on the forehead is suppressed in a bilateral pair of periorbital fields . Without a widow's peak, these fields join in the middle of the forehead so as to give a hairline that runs straight across . A widow's peak results when the point of intersection on the forehead of the upper perimeters of these fields is lower than usual . </P> <P> A widow's peak is a distinct point in the hairline in the center of the forehead; it is a dominant inherited trait . There are varying degrees of the peak . People who do not have a widow's peak have a hairline that runs straight across . </P>

A widow's peak in humans is an example of a(an)