to me, the story doesnt make a lot of sense. all around the universe big rocky giants moved inwards and suddenly became gas giants of the inner solar system, but in ours for some reason Jupiter got big and gracious and it blocked Neptune and Uranus, and more perhaps.

I dont buy it, i think what others have said, that jupiter was pulled out from the inner solar system along with the other large gas giants. and that earth might have been a super earth, but its collision that created the moon threw large portions into outer space.

this 2nd hypothesis makes more sense, especially when you consider that earth is unusually dense. we should have been a larger planet, were like the denser core of something else left behind. Much denser then even venus or mars.