Environment trumps heredity

ENVIRONMENTAL FAC TOR S have a greater impact on an individual's immune system than hereditary factors. This has emerged from a study on 78 pairs of identical twins (almost 100 per cent genetically identical) and 27 pairs of fraternal twins (50 per cent genetically identical). Analyses of blood samples of these twins for 200 immune-system components found that environmental factors, such as exposure to toxins and vaccination, had a greater impact than heredity on about two-thirds of the components. Cell, January 15