There is a very good web site - Gene PD - Frequently asked Questions about Parkinson's at: http://www.bu.edu/genepd/FAQ.htm#FAQ Also the National Institute of Environmental Health Sciences has a Fact Sheet on Parkinson's which nicely summarizes past and ongoing research on the role of genetic and environmental factors. See: http://www.niehs.nih.gov There are many others as well. Try also some of the Web indexes on PD under genetics. Hope these are of some help to you, Linda Herman