Why pubic hair won't grow on the top of the vagina?

Pubic hair typically grows in areas where androgen hormones influence hair follicles, particularly during puberty. The top of the vagina, or the vaginal opening, does not have hair follicles suited for pubic hair growth; instead, hair grows around the mons pubis and labia. Additionally, genetic factors can also determine hair distribution in this region. Therefore, it is normal for pubic hair not to grow on the top of the vagina.