[LimberJim]

This is what Wikipedia says about the fumerase deficiency gene:

“It is believed that Joseph Smith Jessop, one of the founders of the communities, and his first wife carried the mutant allele. According to the Phoenix New Times, the rare disease appeared when their 12th child, Martha Jessop, married her second cousin, John Yeates Barlow, in 1923.”

[brytlea]

Thanks for the info.
susie