pedigree collapse

When the principles of breeding and of inheritance are better understood, we shall not hear ignorant members of our legislature rejecting with scorn a plan for ascertaining by an easy method whether or not consanguineous marriages are injurious to man.
~ Charles Darwin
(The Descent of Man: And Selection in Relation to Sex)

“Seven-Year-Old Charles Darwin in 1816” by Ellen Sharples ~ Charles married his first cousin, Emma Wedgwood and they were the parents of ten children.

Two parents… four grandparents… eight great-grandparents…

If the number of ancestors is doubled in each generation as we go back in time, logic suggests there will be about a thousand ancestors per person in ten generations, and about a million of them in twenty generations. But as we go back in time fewer people were on earth than there are now.

However, one does not usually have to go too far back in his or her family history to find cousins marrying cousins of one degree or another. This actually collapses the pedigree, because when cousins have children together, some of the children’s ancestors are repeated in another line. This can make for a non-branching family tree with very tangled roots! The more cousins having children together on one’s pedigree, the more lines of ancestors will be repeated, and the actual number of one’s ancestors will eventually be fewer and fewer…

Following are the cousin marriages I have found so far on our trees. I will continue to update this page when I discover new connections.

Tim & I are 10th cousins, twice removed. Tim’s 11th-great-grandparents and my 9th-great-grandparents were [7968] Nathaniel Bacon and [7969] Hannah Mayo.

Tim’s great-grandfather, [16] George Lincoln Rodgers married his first cousin, [17] Mary Jane Rodgers, Tim’s great-grandmother. George & Mary’s fathers were brothers, and their grandparents in common were [64] Jacob Rogers and [65] Mahala Bedford.

My 2nd-great-grandfather, [56] William Martin White married his first cousin, [57] Ellen C. Hill, my 2nd-great-grandmother. William’s father and Ellen’s mother were siblings, and their grandparents in common were [224] Oliver White and [225] Lydia (—).

My 2nd-great-grandfather, [58] Reuel Gardner Atwood married his half second cousin, once removed, [59] Louisa Jane Atwood, my 2nd-great-grandmother. Reuel & Louisa’s common ancestor was [472] Lt. Nathaniel Atwood.

My 3rd-great-grandfather, [116] Reuel Atwood married his sixth cousin, [117] Abigail Savery Tillson, my 3rd-great-grandmother. Reuel & Abigail’s common 5th-great-grandparents were [7602] John Howland and [7603] Elizabeth Tilley.

My 3rd-great-grandfather, [118] Ebenezer Atwood married his second cousin, twice removed, [119] Waitstill Lucas, my 3rd-great-grandmother. Ebenezer & Waitstill’s common ancestors were [944] Dea. Nathaniel Atwood and [945] Mary (—).

My 3rd-great-grandfather, [122] Warren Freeman married his double fourth cousin, [123] Elisabeth Weekes, my 3rd-great-grandmother. Warren & Elisabeth’s common 3rd-great-grandparents were [3912] Joshua Hopkins and [3913] Mary Cole; and also [3932] Edward Small and [3933] Mary Woodman.

My 4th-great-grandfather, [232] Nathaniel Atwood married his first cousin, [233] Zilpha Shurtleff, my 4th-great-grandmother. Nathaniel & Zilpha’s mothers were sisters, and their grandparents in common were [930] Nathaniel Shaw and [931] Hannah Perkins.

Tim’s 5th-great-grandfather, [376] Asher Huntley married his first cousin, [377] Betsey Wilder Tiffany, Tim’s 5th-great-grandmother. Asher’s mother & Betsey’s father were siblings, and their grandparents in common were [1506] Consider Tiffany and [1507] Naomi Comstock.

My 5th-great-grandfather, [464] Ichabod Atwood married his first cousin, once removed, [465] Hannah Shaw, my 5th great-grandmother. Ichabod & Hannah’s common ancestors were [944] Dea. Nathaniel Atwood and [945] Mary (—).

My 5th-great-grandfather, [478] William Shurtleff married his first cousin, once removed, [479] Ruth Shaw, my 5th-great-grandmother. William & Ruth’s common ancestors were [1912] Abiel Shurtleff and [1913] Lydia Barnes.

My 5th-great-grandfather, [488] John Freeman married his second cousin, [489] Abigail Hopkins, my 5th-great-grandmother. John & Abigail’s common great-grandparents were [3906] Richard Sparrow and [3907] Mercy Cobb.

My 7th-great-grandfather, [1952] Edmund Freeman married his second cousin, [1953] Sarah Sparrow, my 7th-great-grandmother. Edmund & Sarah’s common great-grandparents were [15618] Thomas Prence and [15619] Patience Brewster.

Last Revised:  15 November 2017

Ancestor Table

11 thoughts on “pedigree collapse”

  1. Hey Barbara, So, if there is no collapse, a person has 4 grandparents, 8 great-grandparents, 16 great-greats, 32 great-great-greats, and so on. How many great-great-greats do you have, then, for example?

    1. So far I have identified 16 of my 32 3rd-great-grandparents, all of them my mother’s ancestors. I doubt I will ever find the 16 on my father’s side…

      My pedigree started collapsing when one of my great-grandfathers married his first cousin so that two of my 4th-great-grandparents are identical to two other ones. 🙂

    2. PS- That means so far, of my 64 4th-great-grandparents, two are repeated so I don’t have more than 62 of them, as far as I know! It’s strange, these concepts make so much sense in my head but I have a hard time describing them with words.

    1. It’s so addictive, Sybil! I simply cannot stop! How lucky for me to have lived long enough to enjoy the era of internet magic.

  2. This is fascinating! So now, it’s frowned on to marry a first cousin, right? But is a second cousin okay? You’re right, ‘back then’ there weren’t as many choices – not as many people in the world, and harder to meet new people more than a few miles away. Now – the choices are enormous. Wouldn’t it be interesting to know how many second cousins marry these days, just in the U.S.?

    1. According to Wikipedia: “As of February 2014, 24 U.S. states prohibit marriages between first cousins, 19 U.S. states allow marriages between first cousins, and 7 U.S. states allow only some marriages between first cousins.”

      My mother’s ancestors were almost all from colonial New England. The Pilgrims had very slim pickings when it came to searching for a spouse! During the terrible first winter in Plymouth 45 of the 102 Mayflower passengers died and most of the survivors quickly picked a new mate from the 57 remaining individuals.

  3. My mind is completely boggled by this!! How did you even do the math? Seems that reading this makes me feel that we are all related less than the “Six degrees of separation”. Very daunting a task you’ve undertaken, good for you building those brain cells.

    1. It is rather mind-boggling, isn’t it? I am terrible at math and still need to count on my fingers to add or subtract, but, has no problem keeping it all sorted out for me. And for some reason ancestor tables make sense to me.

      We are all related! (In theory we all descend from Mitochondrial Eve.) But it’s fun finding out how closely. 🙂

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