Answer: Age and Stress are two main reasons.
Step-by-step explanation:
Age:
Age is a prime reason because as you grow, your bones also grow, causing your skin to stretch, but as you get older, your bones shrink, causing your skin to show stretching from when your bones were still at their peak height.
Stress:
Stress causes faster aging, usually showing on the forehead and around the jaw area. You can age your skin more than a year faster just through stress.
Ways of Prevention
You can start with the skin care products you are using, try using more natural things because your skin wont is as healthy if you a product with many scientific ingredients and preservatives. You have to also always keep it moisturized and not dry cause dry skin causes cracks.
If Your Stressed, you can start by looking for what's causing the stress, then when you find it, find out why it's causing you stress, and when you do that get rid of that stress factor. You also should get a good sleep and give yourself more time to deal with yourself, normally when someone is stressed its cause they arent spending enough time with their self.
Have a nice day!