why some people have lots of pimples?

Not only is this genetic but I believe stress and the environment contributes a lot to this. My genes are pretty good so I don't have much pimples and I try to keep my face clean all the time. Of course that's next to impossible with pollution nowadays.

Environment, Stress and the Food we take is the major reason why we pimples came out to our face. Cleaning/Washing our face is just keeping the dirt away from our faces to clog in our spores. But maintaining this hygiene keeps you away from pimples and making it worst.

Genetics maybe be consider as one factor too. But not really the major cause of Pimples to an person.