Here's a surprising thing: It is possible to cause something to be uncaused. Let's suppose Socrates' parents chose to have only one child and that was Socrates. Let U be any uncaused being whose existence is independent of the decisions of Socrates' parents. Perhaps U is God or the number 2 (or some quantum event if these are uncaused--I think they're not). Consider the disjunctive event E of U existing or Socrates having a sibling. This event has no cause. But if Socrates' parents had had another child, then E would have had a cause, namely Socrates' parents who would have been the cause of Socrates' having a sibling and hence of the disjunctive event. So, by choosing to have only one child, Socrates' parents caused E to have no cause.