I popped up with a theory that nullifies the notions of paradox and/or changing the future by changing the past. It's pretty much the same thing as the theory that every possible outcome to an action happens in parallel alternate realities. But mine adds that if I go back and kill my grandfather, it doesn't create a paradox because the timeline I came from still exists. At the point of change - the killing of my grandfather, a new reality is created. In that timeline, I never exist. But the original timeline, the one I came from, still exists. The new, grandfather-less timeline splinters off without changing the primary one.
So, according to this theory, it wouldn't matter if I went back and changed something. It wouldn't change the life I've lived. The only way change can happen is if I create that reality with my own actions now.
Clear as mud, right?