Acne is a skin condition that causes pimples, blackheads, whiteheads and scars. Acne normally affects the face, neck, back, chest and arms. The severity of this skin disorder can vary from person to person. Typically, people between 12 and 25 suffer from acne. However, there are also men and women aged 30 to 40 who are also prone to this type of skin disease. Here are some guidelines to help you understand more about what causes acne.