"In order for you to ever be born in the first place, someone had to impregnate your mother. "

Right that's kind of a twist on the grandfather paradox. If you don't do it then you would not have gotten the message to do it in the first place. But maybe the old you is just trying to protect his own existence because some other you did the exact same thing to him. You bring up a good point about making new people. I think that time travel would trigger the butterfly effect and ultimately the world would change more radically than one might think. There would be a bunch of new people and allot of old people would probably not exist at all. Meaning the entire history of the future gets changed your family might not exist at all in the future even if you did do it. You make lots of interesting points.