Brian Greene on: Why is does our universe appear to be fine tuned for life?

Why is does our universe appear to be fine tuned for life? Why is does our planet appear to be equally fine tuned for life? Maybe it is because of the same reason. In an enormous amount of slightly different systems (other star systems/multiverse) it is likely that some will be viable for our kind of life.
The mathematics certainly allows the existence of a multiverse it and there is usually a great level of parallelism between the math and reality (eg. quantum mechanics, anti-matter...).