We don't completely understand this process, nor may we ever, but there are several possibilities. Either there is only ONE possible kind of universe that can emerge from the Big Bang because others are not 'self-consistent' and there is only one type of initial condition possible, or there are an infinitude of universe that could have emerged each with its own special set of properties, forces, particles etc. An increasing number of physicists subscribe to something called the Anthropic Cosmological Principle which simply says that we see the kind of universe we do, because we are here to observe it. Only a 'peculiar' universe like ours would end up with living and conscious organisms capable of framing the question in the first place. There may be an infinite number of ways of starting a universe out in life, but only universe that have our kind of natural laws and phenomenology evolve living systems.
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