Why?

Well there was nothing and there became something.

If we take the cause and effect theory which clearly conforms to the evolutionary theory then logicaly we are able to so rewind the cause and effect to a point where there was nothing. Hence, if there is no choice but only predetermined causes, what predetermined something from nothing?

I do not know. You may be right. That's metaphysics. In practise you can't even tell whether the universe is like a movie or a computer game.

I.e. a movie on a film reel consists of frames that are created once and when you watch it looks like a coherent story --- but when you paint over some frames at the beginning, it has no effect on any other frame.

Whereas when you manipulate the state in a computer game --- say, give Super Mario that mushroom --- you change everything that comes later.

And for that straw man theory of causality: You can just exchange it for a theory that postulates a cause for everything _but_ the Big Bang.

(By the way, I do not believe in causality. At least not the kind of mono-causality exhibited in human storystelling, esp. stock market commentators on TV. Strangely I still manage to believe in determinism.)