Identical twins: same body, same brain, same everything ... right?
Well, not exactly. Apparently, the similarity between identical twins depends not only on the body they're born with, but also how they treat that body.
Identical twins in Finland who shared the same sports and other physical activities as children but different exercise habits as adults soon developed quite different bodies and brains, according to a new study summarized by The New York Times. The study attempts to demonstrate the extent to which exercise shapes our health, even in people who have identical genes and nurturing.
Scientists at the University of Jyvaskyla and other Finnish institutions turned to Finland's extensive FinnTwin16 database, which contained twins' answers to questionnaires about their health and medical conditions, beginning when the pairs were 16 and repeated every few years afterward.
The researchers wanted to focus specifically on identical twins in their early- to mid-20s whose exercise habits had gone in complete opposite directions after leaving home — which was pretty difficult to find.
But eventually, the researchers honed in on 10 pairs of male identical twins, one of whom regularly exercised, while the other did not. According their questionnaires, the differences in their exercise routines had mostly started within the past three years.
The scientists measured each young man's endurance capacity, body composition, and insulin sensitivity to determine their fitness and metabolic health. They also scanned each twin's brain.
This is what they found, according to the Times: