RedPenguins. 40% made no sense to me 1 in 40 for parent having MS. NMSS says they think that still low. Please consider facts yourself on this.

Epidemiologic surveys have determined that an individual's risk of developing MS increases several-fold if a close family member has MS. While the average person in the United States has about 1 chance in 750 of developing MS, the risk for a person who has a parent or sibling with MS increases to about 1 in 40. MS. Thus, the risk increases significantly for a person whose parent has MS, but still remains relatively low.

These risk estimates, however, are oversimplifications that can easily be misinterpreted. We now know, for example, that risk estimates can vary greatly depending upon the structure of a person’s family. In families in which MS occurs in many relatives, the risks for any given individual are significantly higher than they are for an individual who has no family members with MS. Risk for MS is also affected in part by a person’s ethnic background and other factors that haven’t yet been clearly identified.

How do we know that genes are not the only factor in determining who gets MS? The identical twin of a person with MS has a 1 in 4 chance of developing the disease. The fact that identical twins of people with MS—who share all the same genes—don’t always get MS, and that more than 80% of people with MS do not have a first-degree relative with MS, demonstrates conclusively that MS is not directly inherited and that factors other than genetics must be involved.