Through breeding, chromosomes are compiled into a new bio-machine (human), which gives the creature its particular gene pool, making it unique.
What I find interesting is the likelihood of a genome forming/separating and evolving into an entirely different genome from the original, the probability has been calculated by renowned mathematicians to be 4x10^110,000, around there, that calculated with the rate of changes in a genome would actually put our 'Sun' at a no longer platform star ranking, it would be MUCH older, or have exploded.