The now and then postings of the discoveries and contributions of the Miller and Bechtold families .
Tuesday, March 30, 2010
genealogy 101: double cousins, McCaffreys
Brother-Sister marry Brother-Sister
Ella McCaffrey marries "Bun" Cole
Florence McCaffrey marries Kate Porter Cole
...and you get...
Double First Cousins!
From Wikipedia, the free encyclopedia
Double first cousinsarise whensiblingsof one family reproduce with siblings of another family. The resulting children are related to each other through bothparents' families. Double first cousins share both sets ofgrandparentsin common and have double the degree ofconsanguinitythan ordinaryfirst cousins. Genetically, they are as related ashalf-siblings, sharing 25% of their DNA (a coefficient of relationship of 1/4).Their coefficient of coancestry is 1/8th or 0.125. While double first cousins have the same coefficient of coancestry (1/8) as half-siblings, they do have higher chances of sharingbothalleles(1/16 vs 0) and lower chances of sharing one allele (3/8 vs 1/2) with each other than half-siblings.
When identical twins reproduce with a pair of siblings, the resulting children are more related than half-siblings but less related than full siblings (they are genetically equivalent to 3/4 siblings) although they are legally double first cousins.
When identical twins reproduce withanotherset of twins (sometimes called quaternary marriage), the resulting children are likewise genetically indistinguishable from full siblings, although they are genealogically double first cousins.
Children of double first cousins are double second cousins to each other. There are, however, several additional types of double second cousins, including the children of two sets of regular first cousins.
Double cousin marriage is prohibited in North Carolina (N.C. Gen. Stat. § 51-3) and West Virginia (W. Va. Code 61-8-12). It is permitted in the other 24 states that permit marriage between first cousins.
[Interesting to note that it is illegal in West Virginia... anti-red-neck legislation?]