Developing MS is not your fault and has nothing to do with your lifestyle or behaviour. Although nobody's yet certain why people get MS, research suggests that it is caused by a combination of genetic and environmental factors.

MS is not directly inherited and, unlike some conditions, it isn't caused by one faulty gene. However, there does appear to be a genetic component - possibly a combination of genes - that makes some people more susceptible to developing MS.

This doesn't mean that your relatives will develop MS too. Even if you have an identical twin, it doesn't mean they will also get MS. (They are more likely not to get MS.) Different research studies have produced different figures and while it's impossible to be precise, the overall chance of your children developing MS is small.1

Strangely, the further you live from the equator, the more likely you are to develop MS. That's one reason why it's relatively common in Britain (and more common in Scotland than in the rest of the UK), North America and Scandinavia, but virtually unheard of in, for example, Malaysia or Ecuador. the reasons for this aren't entirely clear, but it's possible that something in the environment - possibly a virus - triggers MS. 2

Approximately 85,000 people in the UK have MS - that's about one in every 800 - 1000 people (or one in 500 people in Scotland). The majority of people with MS are diagnosed with the condition when they are aged between 20 and 40, though if can, of course, occur in older people and, more rarely, in children. It's also almost twice as common in women as in men.