There are several recognized risk factors in Multiple Sclerosis, although there is no definite known cause.  

Heredity is the first of the known risk factors for Multiple Sclerosis. If no one has Multiple Sclerosis in your family, then your chances of having MS are only 1 in 750. Having a parent or sibling with MS increases the odds to 1 in 100. If you have an
identical twin with MS, your chances are 1 in 4, although both twins do not always have MS. For this reason, many researchers believe that Multiple Sclerosis is not just a genetic disease, although heredity does affect the chances you will have it.

Environmental factors are the second risk factor for Multiple Sclerosis. Research shows that bacteria and viruses, especially at certain ages, can increase your chances of having MS. Alone these infections should not cause MS, but when combined with other risk factors for Multiple Sclerosis, especially heredity, they can greatly increase the odds of having it. The infections that could be related to MS are measles, herpes, chickenpox, rubella, mononucleosis, chlamydia, and some types of flu. These may have the most risk when they are contracted as a teenager.

For some unknown reason, MS is more common in temperate climates such as Europe, southern Canada, northern United States, and southeastern Australia. This geographical factor seems to be most important during puberty.

 Women are 2 to 3 times more likely than men to have MS. This is believed to be due to hormonal differences. Men who smoke are twice as likely as men who do not smoke to be diagnosed with MS.

Age is the fifth risk factor for Multiple Sclerosis. Usually MS is diagnosed in people between 20 and 50. It is possible to be diagnosed during childhood or after the age of 50, but this age range seems to be the most critical.

The sixth risk factor in Multiple Sclerosis the use of cow's milk to infants under one year of age. This is a newly discovered risk, and the reasons are not yet known. Pediatrician's advise against cow milk for infants under one year of age, anyway, so it would be best to be careful. Breast milk is believed to be the best food for infants because it helps the brain develop faster and more fully.

Heredity is probably the strongest risk factor for Multiple Sclerosis, but combining several of these factors together may further increase the risk. Public awareness of these risks of developing MS are important and certainly anyone with persistent neurologic symptoms should seek appropriate medical evaluation.