This may help. "...it has been reported that in cases in which Parkinson's disease afflicts several members of a family, the onset of the disease tends to cluster in time. Normally, if a disorder has a purely genetic basis, onset of symptoms occurs at similar ages, not at similar times. Evidence that Parkinson's disease does not occur more frequently in identical than fraternal twins also argues against a hereditary determinant of the disorder. Page 54, Neurotoxicity: Identifying and Controlling Poisons of the Nervous System (1990 Government Publication.).. Want to discuss Neurotoxin's. Contact me via E-Mail or IM. I'm not an expert ... just a victim like all of you, even you without PD or some other visible disorder or disease. Rudy West NC 61/9 (17 years silent & subtle) [log in to unmask]