Read the paragraph below. Soon after the moving truck departed, I made way next door to greet the new neighbors. A boy was playing in the yard, and I greeted him and introduced myself. In response, the boy ducked his head and mumbled an inaudible reply. Though he smiled, he quickly retreated toward his mother on the porch. When I said, "Welcome to the neighborhood,” his cheeks turned pink, and he disappeared through the open front door.

What inference can be drawn about the boy?