What causes your skin to wrinkle?

Loss of Structure. Collagen and elastin give our skin it's robust character in youth. Age, sun, smoking, illness, diet, genetics contribute to the loss of these support structures over time. Our skin gets weak & folds/pleats in places where muscles force it. Lines on the face also develop from external forces like pressure from sleeping on your side. There are some effective ways of preventing wrinkles...
Wrinkles from sun. Sun exposure ruins the collagen and elastic proteins in the dermis and wrinkles form. Twins who were studied, one with much sun, and one who didn't spend much time outdoors, can look very different from sun-exposed wrinkles. Sunscreen is very important, don't smoke, and use retin-a, antioxidants, and fraxel laser and portrait plasma to cause new collagen to form and replace the damaged collagen.
Aging and sun. Your skin is biologically pre-programmed to age at a certain rate and this is genetically determined and out of our control. Sun exposure can accelerate this aging by causing damage to collagen which starts to deteriorate and thin out which causes the skin to lose its firmness and elasticity resulting in wrinkles and sagging. Other factors include smoking, poor diet, facial expressions.
Sun, smoking and Age. Wrinkling worsens with age. It can be dramatically worsened by sun exposure and/or cigarette use. The sun and tobacco accelerate the aging process which leads to loss of skin thickness and elasticity. Protect and slow damage by good skin care and sunblock use (see your facial plastic surgeon or dermatologist for specific recs. Treatments available include botox, fillers, lasers, peels and more.
Causes of wrinkles. Wrinkles are caused by extrinsic & intrinsic reasons. Extrinsic reasons are sun exposure, smoking, environmental pollutants, tanning beds. Using sunblock helps with this. Intrinsic wrinkles are due to aging, menopause/andropause (hormone replacement helps, chronic diseases. Patients who are healthier & limit sun exposure generally look younger. Ethnic skin looks younger due to the extra melanin.
Wrinkle reasons. Many factors lead to wrinkles. Some is due to external factors like sun exposure and smoking, and some is due to internal factors, such as loss of bone, muscle, collagen and fat as we age. Genetics also plays a large role. There are many options to address wrinkles, including prevention and treatment.
Many factors. Wrinkling is caused by loss of elasticity in the skin. Age, ultraviolet light, smoking, and heredity all play roles in how fast and how much the skin wrinkles. Skin aging can be slowed by proper skin care, uv avoidance, and the use of anti-oxidants. Some laser treatments can reverse aging by tightening loose collagen and elastic fibers.
Skin wrinkles. Skin wrinkling is a complex process due to thinning of the deeper layers with age making it more vulnerable to repeated folding by the underlying muscles. This is worsened by the loss of elasticity due to elastin decrease in the skin. The skin has increasing difficulty repairing itself after injury (solar, chemical, mechanical, etc). Increases in the superficial layers of dead skin also occur.