Marie, that is really sad about your classmates. It is interesting that 1/9 of your class ended up with MS. It is pretty close to the numbers in the study (below), which puts genetic susceptibility to MS in a really clear way that I like,
over 99% of individuals seem genetically incapable of developing MS, regardless of what environmental exposures they experience
"The Causal Cascade to Multiple Sclerosis: A Model for MS Pathogenesis"
Douglas S. Goodin, Department of Neurology, University of California San Francisco, San Francisco
http://www.plosone.org/article/info%3Ad ... ne.0004565