Is it possible to wrinkle at age 18?

Yes-But It's Early. We usually have enough collagen and elastin at age 18 to keep our skin looking young and fresh. That being said, genetics, wear & tear, general health, excessive tanning, and smoking could contribute to early aging with respect to wrinkles. If the wrinkles bother you, take the time to ask a physician what choices you have to prevent, protect, and correct for the lines. Hope this helps!
Yes. Too much sun and smoking can cause wrinkles to form very young. Being very expressive with facial muscles (squinting, frowing, smiling) can cause early wrinkles to form. Also sleeping on your face can cause early lines to form.
Wrinkles at 18, yes. Unfortunately we can see sun damage/wrinkles in some people early on due to their complexion, sun exposure, genetics, & chronic diseases. If you already have them, you need to decrease sun exposure, use a sunblock and start using retin-a, the only cream that can help correct wrinkles over time. Start low and build up b/c if it is too harsh, you won't use it don't smoke & drink in moderation.
Few wrinkles at 18. It is possible if as a toddler and young child you had a lot of sun exposure without sunprotection, are out in the elements, excessively use exfoliants and acne products that dry and irritate the skin. With the latter, the resultant dry skin can looked creased when the skin folds over contracting underlying muscles such as near the eyelids with smiling and squinting. These improve w good skin care.