I am a free agent and morally responsible for my actions only if my actions are under my control. If my actions originate from events which have no cause, they happen randomly and are not under my control. If my actions originate from events which have no cause, I am neither a free agent nor morally responsible for my actions. The Theory of Agency. All events are caused.
Some causal chains have beginnings.
Human persons are self-moving substances, capable of being first causes of motion in a causal chain.