 Hi, I am Dr. Sachit Abraham, Consultant Dematologist at Manipal Hospital in Bangalore. Like I said before, acne is a combination of genetic and environmental factors with hormones. The teenage hormones are, you know, at the maximum, at the time of the teenagers. That is why, and under the influence of the hormones, the bacteria that produces pimples tend to proliferate and blocks the pimple glands to produce this acne. So basically, it is a combination of genetics and environmental factors with hormones. The hormones start spurting in the teenage years, that is why you get acne.