This question already has an answer here:
There was an episode of The Twilight Zone involving time travel and as it turned out some things can be changed but other events can't and it seems to me it's possible to avoid the time paradox.
For example, at first someone else was the father and Sarah raised him by herself. At some point Skynet is created starts the war and after losing sends the terminator back in time to kill her. Kyle goes back in time and becomes the father of John creating the time loop.