How does Beah know Gasemu?Chapter 11

Beah grew up in the same town where Gasemu lived. He'd known the man since he was a boy.

"He used to be one of the notorious single men in my town."

“Are you still a troublesome boy?” He pulled on my nose. “There is no time to be troublesome these days,” I said. “I see that you look very sad. Your forehead used to glow naturally when you were just a child. Your parents and I used to discuss how unusual that was. We thought it was because you were happy all the time."