Here are some interesting stats from the article Multiple Sclerosis: Hope Through Research about what can increase a person’s risk of getting MS:
Gender:Women are 2 to 3 times more likely than men to become diagnosed with MS. Researchers believe that the hormonal differences in men and women account for higher risk in women. Hormones have a clear interaction with MS and are known to be protective during pregnancy. This relationship is just beginning to be explored.
Family:If no immediate members of your family have MS, then your chances of having MS are 1 in 750. If you have a parent or sibling with MS, your risk increases to 1 in 100. If you have an identical twin with MS, your risk is 1 in 4. It is interesting that identical twins do not always both have MS, even though they share 100% of genetic information. This fact is why researchers have concluded that MS is not simply a genetic disease.
MS occurs more often in people of northern European descent, but other ethnicities may also have MS. This could be explained by the fact that MS occurs more frequently in regions that are farther from the equator (above 40 degrees latitude). Rates of MS in these northern regions can be as much as 5 times higher. If a person migrates from a high-risk region to a low risk region before the age of 15, they take on the lower risk. Researchers think that puberty (hormones) and geography may somehow interact to increase MS risk.
Most MS is diagnosed between the ages of 20 and 50, thought both childhood and late onset MS are possible. This is usually the age at which the first symptoms appear and a person begins the process of getting diagnosed with MS.
You can learn more about risk factors of MS at the National Institute of Neurological Disorders and Stroke.
Multiple Sclerosis 