I just found this little paragraph about MS. So far neither Matt nor Annie has any signs of it nor do any of Bonnie's children but they COULD.
While multiple sclerosis (MS) is not believed to be a hereditary disease, having a family history of MS (particularly in a parent or sibling) does make a person more likely to develop it. In a family in which one parent has MS, the risk that their children will develop the condition is estimated to be between 2 and 5 percent. Studies have shown that there is a higher prevalence of certain genes in areas where MS seems to cluster, as well as in some families where there is more than one person with MS. It is speculated that MS develops because a person is born with a genetic tendency to react when exposed to some environmental agent that triggers an autoimmune response.