This principle of causation is so fundamental that if I said that the chair you are sitting on, which must have had a beginning, just popped into existence without any cause, you might justifiably think I need a psychiatric assessment!
One of the most established principles of logic / science / reality is the principle of causality: something that has a beginning has a sufficient cause.
The first choice for the role of Marty Mc Fly was Michael J. However, he was busy filming his television series Family Ties and the show's producers would not allow him to star in the film. During filming, Stoltz and the filmmakers decided that the role was miscast, and Fox was again approached for the part.
Now with more flexibility in his schedule and the blessing of his show's producers, Fox managed to work out a timetable in which he could give enough time and commitment to both.
Just a moment’s thought confirms this—something which had no beginning has no need of a cause.