For completeness: Donuel has this bit right: If everything was symmetrical we would not exist but somewhere the symmetry broke and our universe became possible. Had the Big Bang resulted in equal amounts of matter and antimatter, there'd have been a massive fireworks display, leaving only a cloud of gamma radiation.

Working out what broke symmetry is left as an exercise to the advanced theoretical physicist: your task, if you choose to accept it, is to permit symmetry to be broken without also breaking the astonishingly close agreement between currently-accepted physics and observation; predictions which can't be tested won't count. You are permitted to use both sides of the paper, but not at the same time. Good luck.