Younger siblings reduce risk of multiple sclerosis

Children that live with younger siblings in their first six years are less likely to develop multiple sclerosis in later life, according to a new study. As New Scientist http://www.newscientist.com reports, the finding backs the so-called "hygiene hypothesis", which proposes that exposure to infectious bugs early in life - lurking in household dirt or carried by younger siblings - reduces the risk of allergic and autoimmune diseases by stimulating the immune system.