What is the real cause for acne?

No single cause: Acne is a poorly-understood process involving one's personal biology, hormonal status, keratin thickness, personal bacterial microflora, and probably a bunch of cytokine parameters we don't begin to understand. What we do know is that it's basically unrelated to hygiene, diet, or lifestyle, and anyone offering simplistic answers is both wrong and cruel.

There can be many: Causes, from genetics, bacteria, irritants like washing too much, hormones, the list goes on.