Some people secrete genetic material with Bodily fluids (sweat, saliva, etc.), others don't. The majority of the modern population (over 80%) are secretors.
Which leads to an intriguing question of the origin man, as most primates studied aren't secretors (whats termed nonsecretor, or nonnie in the Blood-Type Diet).
There is a legitmate case being made that some of us did not evolve...I am not saying that I really follow Creationism, or I am an 'alien believer' either.