Even though identical twins are as close to genetically identical as possible, changes in lifestyles can affect two people very differently. Take for instance smoking, and the damages it can cause over a lifetime.
Because identical twins are almost genetically identical, they make for an interesting test group when evaluating differences in lifestyle over a prolonged period of time. If you mix in the different factors, say for instance smoking, you can get an accurate picture of the effects of smoking or not on a nearly identical genetic sample. But in this case, you dont even need fancy tests to see the difference in twins that smoke and their counterparts who dont smoke. The difference is blatantly obvious.
WHICH TWIN SMOKES?
in this case, both brothers smoked, but the twin on the left quit 14 years prior to the twin on the right.
Again, both of these twins smoked, but the twin on the left has been smoking for 17 years longer than her sister.
the twin on the right has never smoked, while her sister smokes 10 or more cigarettes a day for 14 years
The woman on the right is the smoker between these two.
This one is a little easier. The woman on the right is clearly the smoker between the two.
Again, the woman on the left is obviously the smoker.
Looking at these pictures, we are reminded that we dont all have a genetic double to compare ourselves to, but the effects of smoking are clear either way.