With age comes wrinkles, but the cause of those grooves, creases, lines and hollows is more than just the natural aging process.

Heredity plays a major role, and the environment you subject your skin to, from excessive sunlight to harsh pollution, could be stripping your complexion of its youthful glow.

Visible signs of aging on the face may be inevitable, but the causes that lead to its severity aren't all out of your control. Both intrinsic and extrinsic factors impact the wrinkling of your skin, with intrinsic being heredity, and extrinsic being those from your environment, such as smoking, alcohol, pollution, diet, wind, and (the big one)  sun damage.

Sun Damage

The sun's harsh ultraviolet (UV) radiation makes it the leading cause of aging skin and skin cancers. The rays break down collagen and elastin fibres, the major structural protein in your skin, thus causing slackening, sagging, and, of course, wrinkling. Sun damage, or photo-aging, also leads to pigmentation problems, such as freckles, yellowing, visible blood vessels and dark "age spots."

Smoking and Pollution

In addition to decreasing your chances of living to a ripe old age, cigarettes also decrease your likelihood of growing old gracefully: the act of smoking pinches the skin around the lips, causing deep wrinkles over time; the resulting decreased blood supply diminishes nourishment to the skin; and the smoke itself affects the skin's clarity - and all of these factors cause premature aging of the skin. Pollution, too, harms the skin's health.

According to dermatology expert, Dr. Heather Brannon, most of the photoaging effects occur by age 20 and the amount of damage to the skin caused by the sun is determined by the total lifetime amount of radiation exposure and the person's pigment protection.

The Elements

Wind and cold strip the skin of moisture and can cause temperature-induced flushing that, when severe enough, can cause capillaries to break.

Dehydration

Dehydrated skin lacks water and will also more prominently show the signs of aging, since it lacks the moisture that will give it a fuller, more vibrant appearance.

Heredity

Preventing as many of these environmental factors as possible will help you maintain healthier, younger looking skin, but dealing with the intrinsic factors is much trickier, since there's not much you can do to change your genetics. Angie MacIntosh, the esthetics manager and clinical esthetician at Spirit Urban Spa, says predicting your old-age skin is as easy as taking a peak up the family tree.

"You look at your mother and what she looks like, and chances are that's what you're going to look like," says MacIntosh. "If your grandmother had great skin, chances are you're going to have great skin."

Heredity not only influences the severity of wrinkling, but also the facial expressions we make that can lead to deep wrinkles, says MacIntosh, and Keltie Perritt, the clinical skincare therapist at Landing's Surgical Centre agrees. We often get wrinkles - as opposed to fine lines - where we carry tension or where our faces naturally fold or crinkle in response to emotion, says Perritt. A furrowed brow, a full-face grin and angry, pinched lips all lead, with consistent repetition over the years, to wrinkles on the face.

The Birth of a Wrinkle

A wrinkle forms when the factors above cause a breakdown in the lower levels of the skin, where our skin's support system lies, creating a depression. And more superficial fine lines are often a sign of dehydration in aged skin.

Natural Aging Process

Along with the extrinsic factors that create an unhealthy environment for your skin, the natural aging process isn't working with you, either. Over time, your skin's sweat and oil glands will shrink in size and number, and your skin will also suffer a decrease in its ability to retain moisture, both leading to dryness. Beneath the epidermis (the outer layer of your skin), the dermis also feels the effects of aging. The  dermis layer will thin, the collagen it produces will diminish, and the elastin fibres that give it its elasticity will wear out. Further below the dermis, fat cells also begin to atrophy, robbing your skin of its youthful plumpness. This aged, dry, weakened, and dull skin leads to more noticeable sagging, wrinkles, and fine lines.

And then you add the sun to the mix. Sunlight causes collagen to break down at a higher rate than mere chronological aging, and causes the accumulation of abnormal elastin, which leads to the production of large amounts of enzymes called metalloproteinases. This enzyme is supposed to repair sun-injured skin, but the process doesn't always work well and some metalloproteinases actually degrade collagen. If the skin is rebuilt in this imperfect way repeatedly, wrinkles will appear.

Free Radicals

Other extrinsic factors in the aging process, such as pollution, cigarette smoke and herbicides, create free radicals: your skin's enemy when produced in excessive amounts. These unstable oxygen molecules, containing only one electron instead of two, are made during many of the body's normal chemical processes but, when formed in excess, can cause damage to cells as the molecules scavenge other molecules for another electron. Perritt uses a party-scene analogy, where four girls and three boys are in attendance, to demonstrate the destructive power of free radicals. One girl meets a boy, and shortly after a second girl comes and steals the boy away from the first. Another girl then approaches the second and steals the boy, while the first goes off and steals someone else's date - and so the chain-reaction conflict continues.

"There just aren't enough boys to go around so everyone is stealing them from one another," says Perritt, adding that in the same way the party-goers are stealing, "all the cells start stealing from each other, and so there's not only cells dying, but there's that irritation happening within the skin."

Along with damaging cell membranes, free-radicals can alter genetic material, possibly contributing to various skin disorders, including wrinkles and cancer.