Bald Spot Occurs Every Other Year, Then Regrows

I have an occipital baldness. My family thinks that I have pulled it out. In actuality, my son has the same weak spot. My dad had this circle shaped baldspot on his occipital scalp. I noticed that when I shave/taper this area. It will grow back. Sometimes long sometimes short straight hairs will protrude.. At any given rate, the baldspot on the occipital area will occur every other year. Why does this happen?

I would have to render a guess. This is the first time I can remember having this question put to me. Synchronous hair cycling is something humans are not supposed to do. It is possible that your hair in this area has a shorter geneticaly programmed hair cycle than the surrounding hair. This would produce a bald area in the hairs that have a shorter hair cycle, but I would doubt that it would be a complete bald spot — rather, a thin spot. If you are near one of my offices in California, I would agree to map out your balding spot and compare it to the surrounding scalp. A study of the hair shaft thickness may demonstrate the answer to your question.