Universes appear randomly due to quantum fluctuations. Most collapse after a fraction of time, a few inflate to critical size. All universes start off in a very similar way, each with all possible histories ahead of them. In later stages, different universes differ immensely.
The Grand Design
The laws of nature seem mysteriously crafted to allow for complex life. Scientific explanations involve the existence of multiple universes with different sets of laws. Thus, a universe with our set of laws is no more special than the unique configuration of our solar system or the very planet we live on.