06 July 2008

Jesse Helms – A Fatal Case of Pedigree Collapse?

Jesse Helms died recently of “natural causes” and I’m thinking maybe it was because his pedigree finally collapsed completely. A Helms through and through, he had a family tree that was more like a family shrub.

Pedigree collapse is what happens when cousins marry. Their kids get less ancestors because the cousins share the same grandparents. If the parents were not related, the kids would have 4 sets of great-grandparents. But if the parents are first cousins, one couple takes up two slots and the kids have just 3 sets of g-grandparents.

Same thing happens when 3rd cousins marry. They share the same g-g-grandparents, so those branches on the high end of their kids’ family tree get pruned. The kids get 15 pairs of g-g-g-grandparents instead of 16. No big deal, happens to all of us sooner or later. Demographers say that the family tree of a typical English child born in 1947 would have 5% of the ancestor slots filled by duplicates in the generation living in 1492.

In the case of Jesse Helms, his paternal grandfather Joseph Helms had just 12 sets of g-g-g-grandparents instead of 16. Five of Joseph’s 8 great-grandparents were grandchildren of John Isaac Helms and Ann Tilghman who were born in the 1690s.

To make it less abstract, imagine that your parents were first cousins who married each other and had you and your brother. Your brother married a woman from out of town but you married a child of one of your parents’ other first cousins. Your son and your brother’s daughter married and had a child. This describes Jesse Helms’ Grandpa Joseph.

But wait, there’s more. Grandpa Joseph married a cousin who had one quarter of her g-g-grandparents slots filled by grandchildren of John Isaac Helms and his wife Ann. Grandpa Joseph and his wife were the parents of “Big Jesse” Helms, the father of the recently departed Jesse Helms.

Oh, and by the way, the late senator's mother was Ethel Helms, another descendant of John Isaac Helms and his wife Ann.

Jesse Helms’ peculiar ancestry was explored by John Anderson Brayton in the December 1991 NEHGS NEXUS. You can read more on the fascinating topic of pedigree collapse [ overview ] [ in-depth] or analyze Jesse Helms’ pedigree yourself.


A. Spence said...

Wow how odd!! I'm sure there are always cousins that happen to marry..but so many..wow.

misce-Laini-ous said...

Sounds like my Baldwins, Smiths, and Crittendens. That line looks like a kudzu vine!