It depends on which version of Cyclops as to how he gets his optic blasts or even how his powers work, but in most of them he gets his optic blasts during puberty like most mutants do. In no iteration that I'm aware of has he ever been born with his optic blasts. I imagine that would be incredibly difficult for writers to play with given how dangerous and destructive his blasts are. There ARE mutants born with their gifts, but most tend to develop them during puberty.
The resulting fall from the burning parachute as a child is referenced as reasoning behind why he's unable to fully control the blasts. The control issue is usually explained away as brain damage, repressed trauma, a mutation that never fully developed, etc.
