I know Woody Guthrie also. Great folk influence but had Huntington's, a horrible disease that is completely hereditary. If a parent has it, there is a 50% chance that the child will have it. Arlo was afraid to take the test for years, but he missed it.
It is in my family as well, a beloved niece inherited it. The thing about Huntington's is that the people are usually extremely talented and intelligent. Maybe someone will figure that out someday/