Time Travel Theory

the grandfather paradox

So let's say you got back in time but accidentally landed on your grandfather who's still a child
What would happen?
Will you ceast to exist ? but then how will you go back to the past

Or will you destroy a branch in the many world interpretation

Or will you marry your grand mother and become your grandfather which then will die again when you're younger self go back in time and accidentally land on your grandfather/you again?

That's the grandfather paradox