Friday, December 4, 2020

The Story of Bernadette: Part 2 - The Problem of Endogamy

The Story of Bernadette - Part 2
Regional  endogamy within the Alpine valley of Bernadette's ancestors resulted in generations of marriages between the same families, frequently with the nuptial couple having the relationship of third or fourth cousins. Sometimes siblings from one family married siblings from another family, such as two brothers marrying two sisters from a family their parents had chosen. The resulting offspring of the two couples are "double first cousins" to each other, creating somewhat of a nightmare for DNA analysis as double cousins are related through both their maternal and paternal lines. The shared DNA of double cousin can be skewed since they often have additional DNA in common, more than what is found in a typical cousin relationship. This situation is known as "pedigree collapse" and is common in endogamous societies where everyone is related to everyone else.

I would soon learn how the issue of endogamy played an important factor in my attempt to untangle Bernadette's DNA results. 

The Story of Bernadette - Part 2


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