The two-egg twins Anita and Barbro have been involved in a study on aging that has been going on since the 80s.
Researchers believe that twins are a perfect way to investigate how heredity and the environment affect aging, as they become a kind of "natural experiment".
We all age in different ways, and it is genetics that decides the most.
But when it comes to cognitive diseases, there are things you can do yourself to influence.
Even if you have risk variants of the "dementia gene" APOE, you can improve your chances a lot if you live a healthy life.
- It is never too late to change your life and influence the environment, says Sara Hägg, associate professor of molecular epidemiology at Karolinska Institutet.
See in the clip above which factor affects aging almost as much as smoking.
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