In the 1988 movie "Twins," Julius and Vincent Benedict (played by Arnold Schwarzenegger and Danny DeVito) are the result of an experiment to produce the perfect child. And you're supposed to accept that the two are genetically identical — yet, in outward appearances, polar opposites.

While that premise may be hard to believe, finding adult twins who have developed differently is exactly what a team of Finnish researchers set out to do.

They eventually located and studied 10 sets of male identical twins ages 32 to 36 who had divergent lifestyles (one was physically active, the other sedentary), and what they discovered was something you should be aware of.

As you could have guessed, the inactive twin was fatter, and had less endurance and increased insulin resistance, signaling the onset of metabolic problems.

But because the twins’ diets were similar, researchers thought food choices weren't what caused the health differences.

The real surprise? The active twin's gray matter was more robust than the slacker twin's, especially in areas of the brain involved in motor control and coordination.

There are two important takeaways from this:

1. Genetics isn't destiny. You can opt to be healthy, and regular exercise is an important component of that. Take 10,000 steps a day (no excuses) and strength train with hand weights or stretch bands two to three days a week for 30 minutes.

2. Exercise protects more than your muscles and heart from disease; it protects your brain. So get smart about physical activity!