Wednesday, September 29, 2010

Half-Cousins, Dick Eastman & Genetic Genealogy

Dick Eastman ignited a firestorm of discussion on Monday when he announced one of his pet peeves was the term "half-cousin". The term is used to describe a person with whom one shares only a single great-grandparent. The great-grandparent in such a case has had two or more spouses. In his Eastman's Online Genealogical Newsletter, which he with some justification claims to be "the most popular online genealogy magazine in the world.", Dick invoked two forward thinking institutions, the Catholic Church and Black's Law Dictionary, to prove that there is no such thing as a half-cousin.

Dick, that kind of thinking is so 20th Century! Perhaps it belongs in an even earlier one. Black's Law Dictionary did not add a definition for "intellectual property" in its editions until 1999. Long before that leading law schools included whole courses called "Intellectual Property Law" and large firms had practice groups that specialized in it. As early as 1845 the term was being used in legal decisions. The drafters of the US Constitution provided for it decades earlier. And when did the Catholic Church recognize that Galileo was right in some of his theories? 

Whether or not terms like half-cousin have legal or religious significance, many of Dick's readers have pointed out that it offers a specificity that is often useful. Nowhere is this more obvious than in the area of genetic genealogy. A first cousin shares twice as much DNA with you as does a half-cousin. Dick's conclusion that a half-cousin is really a second cousin would resolve that distinction. However, in so doing it muddles the distinction about how many generations back a second cousin really is. Is a second cousin one who shares two great-great-grandparents (and no great-grandparent) with you? Or is it one who shares a single great-grand parent with you as well as two great-grandparents. This kind of legal, religious and genealogical "heir splitting" may be far to technical for some genealogists. However, it does have a precision that is useful in some circumstances.  

In the last several years DNA has separated some of us from others we previously believed were our biological cousins. Many of us have discovered that we have not shared a common male ancestor in more than a millennium with other supposed cousins with whom we share a common surname. That is longer ago than surnames have been in use. In other words our surnames sprang up independently. Over the years and decades we have bonded as we shared our surname research. As a way of recognizing this bond we still consider ourselves to be "cousins in genealogy".

1 comment:

  1. According to Elizabeth Shown Mills, CG, CGL, FASG:

    "Cousin," used generically, could be various relationships; but everything I have studied on the subject contends that "first cousin" has always been a precise degree of kinship (genetically and in traditional church calculations) --with qualifiers such as "first cousin once-removed" and "half-first cousins" to identify relationships that do not carry the full complement of genetic kinship one would get if the cousin's mother were a full sibling rather than half-sibling of one's own mother.

    I checked this just now against a few genetic sites on line. Some of those that define half-first cousin are

    APG-L Archives (Association of Professional Genealogists)
    Tue, 15 Mar 2005 12:56:16