Researchers do not yet understand the causes of MS. Some suggestions for causes and contributors are listed below.
Genes and family history
MS is not directly inherited from parent to child. There's no single gene that causes it. Over 100 genes might affect your chances of getting MS, but genes are only part of an ongoing story where much research continues in to the origins of MS. MS tends to be familial, so people with a family member who has MS may be more at risk. The highest risk is between identical twins where the risk of developing MS is increased.
MS is most common in areas of temperate latitudes, suggesting that climate contributes to lifestyle or other risk factors for MS.
Ongoing research suggests that infection with Epstein Barr virus (causing glandular fever) is linked to MS. However, most people who have had this virus do not go on to develop MS. Therefore infections may play a role in MS alongside other factors.
There's increasing evidence that low levels of vitamin D (the sunshine vitamin), especially before you become an adult, could be a factor in why people get MS.
Foods such as oily fish and eggs can also provide vitamin D. Some neurologists favour vitamin D supplements but these need to be carefully controlled.
Recent research indicates some lifestyle factors may increase your MS risk. Smoking and being overweight are two such factors.