Why do we get acne well beyond our teenage years? The answer is complex. Myriad factors — including genetics, environment, stress levels, hormonal changes, medical conditions and diet — can lead to blemishes at any stage in life. Some of these triggers can send sebaceous glands, the tiny organs that lubricate your skin with oil, into overdrive, clogging your pores. That buildup of oil and dead skin can then become a breeding ground for acne-causing bacteria. While some variables aren’t always in our control, the best defense against adult acne is a consistent, strategic skin care routine. (A few other basic rules: Try to keep your hands away from your face as much as possible, use a clean towel after cleansing and wash your bedlinens weekly.)Here, a simple regimen that aestheticians and dermatologists suggest for managing breakouts at home.