Why are most identical twins easier to tell apart as they get older?

The effects of the environment on the skin, in combination with diet and exercise and lifestyle all take their toll on a person. One twin may live a less healthy lifestyle or another may spend more time outside in the sunshine. All of these factors play a major part in how we look when we are older (even down to certain wrinkle formations).

If the twins had exactly the same lifestyle, ate exactly the same foods, the difference between them would be much less noticeable.