It is a widely held belief that environmental factors may also play a role in the onset of Multiple Sclerosis. The medical community recognises that MS is more common in the populations of countries situated further away from the equator. In Canadaand northern European countries (particularly Scandinavia and Scotland, for example), there is a high incidence of MS, which may reflect a specific susceptibility in those populations.
What is likely is that MS develops as a result of both genetic and environmental factors. A person born with a genetic susceptibility, who is also exposed to an unknown environmental factor(s), is at risk of triggering an autoimmune system response such as MS.