Monday, December 9, 2013

Pedigree Collapse

Whilst resting my eyes I thought about pedigree collapse as that has been an interesting discussion along with the most recent common ancestor on the lists.

 In my family I have a number of cousin marriages so that I have experienced pedigree collapse although not closer than my 3x great grandparents.

The first occasion is my Knight family (Ellis Knight and Eleanor Knight share the same 3x great grandparents Knight (Henry Knight and Mary Oliver). The impact is at the 6x great grandparents level where I have two less because of Ellis and Eleanor being related.

The second occasion is my Routledge family (Thomas Routledge and Elizabeth Routledge share the same Oakshaw Routledge line with both of their fathers being of this line and Elizabeth's mother is also Routledge. One generation back 3/4 grandparents are Routledge and two generations back 6/8 grandparents are Routledge surname and three generations back this becomes 13/16 Routledge as one of the other lines has a Routledge further back. Of these 16 individuals only four of them are distinct and the other twelve are the same four repeated three times. Hence at the 6x great grandparents level there are only eight instead of 16 so a reduction of eight more.

The third occasion is my Carter family (Thomas Blake was my 3x great grandfather and two of his grandmothers were sisters). The impact is at the 6x great grandparents level for me (3x for Thomas) and he has Richard Carter and Elizabeth Musprett as two sets of his great grandparents thus reducing his great grandparents to six so a reduction of two more at the 6x great grandparent level.

The fourth occasion is also in my Blake family although further back so does not affect the 6x great grandparents (Richard Blake married his first cousin Johane Blake and they were my 11x great grandparents). But the impact further down is important as well.

I have a few more lines that I suspect may be cousin marriages but still working away at that. But already at the 6x great grandparent level I have 10 less. Since we have 128 6x great grandparents I only have 118 and possibly less than that as I have not yet determined other possible cousin relationships.

 Although all of my ancestors ultimately were either born in England back as far as I have traced them or are one of my three Canadian born ancestors (all of whom have English ancestors - my mother, her father, his mother and all were first generation Canadian on at least one side (both of my great grandmother's parents were born in England)), I do not have any close cousin relationships until I get back to the 3x great grandparent level. My father's families were all clustered in the Hampshire/Dorset/Wiltshire area and my mother's families were on her father's side from Devon/Somerset and Cumberland/Yorkshire and from her mother's side from Warwickshire/Staffordshire/Leicestershire and London/Surrey. There did not seem in any way that they would ever be related until I discovered that my Question family had married into the Blake family of Somerset. However, I have not found any link between the Somerset Blake family and the Hampshire Blake family but the similar name was quite interesting.

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