when going through puberty hair grows in numerous places. Pubic hair serves the purpose of keeping your genitals warm but whats the purpose of gooch hair?  The gooch is the skin between the scrotum and the anus.

Although I am not aware of strong tests of the various hypotheses, broad concensus is that pubic hair is functional in several ways that may include some or all of: reduction of friction/chafing that could otherwise irritate sensitive areas; hosting beneficial bacteria with antibiotic properties that reduce infection risk; involvement in pheromone signalling for mate choice; visual signal of maturity status for mate choice). Insulation is not generally considered an inportant function of pubic hair.

If you have ever had to take a long walk in wet clothes you will recognize that chafing in the "gooch" area is far from pleasant.