According to George Ebers from the Wellcome Trust Centre for Human Genomics at Oxford, the true causes of multiple sclerosis (MS) may be neither in the genes, nor in the environment as such. The clue, as he has come to conclude after decades of research in the field, is in how the environment interacts with the signposting that affects gene expression, known as epigenetic markers.
I wrote a feature about this work for Oxford Today, which is now available online (free access to all):
Piecing together the causes of lives torn apart
Oxford Today Volume 22 Number 2, Hilary 2010, pages 20-21
The printed version comes with a nice big picture of cellist Jacqueline du Pre, whose life and career were cut short by MS.