Re: scar? on underside of scrotum
It is where the body joins itself together when in the womb after it was decided what sex you were going to be. The first few weeks in the womb the body develops as neither male nor female then branches out to make the sex organs.
You will see similar traits on the underside of your penis, and in the perineum under the scrotum.
Quite normal, more obvious in some people than others thats all.