Saturday, January 23, 2010

I'm My Own Grandpa

Back in 1948, country music duo Lorenzo and Oscar released a novelty record called “My Own Grandpa.” It is a humorous story about how a man through a series of marriages became his own grandfather. Outside of Woody Allen and Bill Wyman, this scenario is probably not likely to occur – although the possibility exists. While the marriages in the song were to non-blood relatives, there is a certain amount of shame that our society has associated with marriage between relatives.

Although this stigma exists, consanguineous marriages do happen and it has probably happened in your family – wait, let’s change that, it definitely occurred in your family, my family, and all of the families on earth. In some cases, these marriages occurred when families wanted to keep real estate or wealth within the bounds of families. In other cases there were distinct religious or cultural reasons to confine marriages to one group of people.  The impetus for cousins marrying could have been pragmatic because the availability of suitable mates was low. This was often the case in isolated rural areas. To recap, there may have been monetary, cultural, or convenience reasons for marrying a relative.

Even in our culture, the idea of marrying one's cousin was not uncommon - nor was it considered unusual.  When doing research on a Civil War unit (the 9th Pennsylvania Reserves), two of the officers were among those who married their first cousins. Neither case was because of a low availability of mates.  One was Dr. Joseph Augustus Phillips, the unit's surgeon who later served as the Surgeon General of Pennsylvania.  Another was First Lieutenant George Hamlin Bemus (who later commanded his own regiment as colonel). 

Following the war, both men held prominent positions in their respective communities of Pittsburgh and Meadville, Pennsylvania.  Neither were stigmatized because of these unions. In fact, the local histories that chronicled their biographies considered these unions as a mark of honor.

Pedigree Collapse


Although we may not be able to identify such marriages in our families, it had to happen at some point and it happened more than once.  When we think about the number of ancestors that double every generation, the chances of being related to ourselves increase. Think about it, we have 2 parents, 4 grandparents, 8 great grandparents, and 16 great great grandparents. If were to exponentially calculate our ancestors back to the time of Alfred the Great during the mid to late 10th century, we would have at that time 68,719,476,736 living ancestors. When you consider that 68 billion is 10 times the number of the current population of the earth (estimated at 6.8 billion), this is an impossibility.

Therefore, we would have to be related to ourselves – everyone of us and in numerous ways. Comedian Jeff Foxworthy observed, “You might be a redneck if your family tree does not fork.” Genealogists call this phenomenon “pedigree collapse.” While it does not only mean that closely related cousins marry each other (although this probably did happen too), it can show that couples may share an ancestry dozens of generations in the past. Even over time and distance, this is possible.

One branch of my ancestry, the Maneval/Manewal family provides two examples. In the first instance, a daughter of the earliest known progenitor of this lineage married into the Ozias family in the early 18th century. In the late 20th century, Ozias and Maneval descendants in Missouri had an accidental connection that was not prompted by genealogical research and ended up marrying one another. 

In the last 10 years, a grandson of my cousin met a young lady in Germany who, when comparing notes, ended up being a descendant of one of my great-grandmother’s siblings. This was a purely chance encounter that was not prompted by families searching for one another.

Relationship and Genetics


In our last installment, I dealt with our unique genetic milkshake that determines our physical and personality characteristics. We will share exactly 50% of our genes with our parents and children; however, with other relatives it is variable depending on how much shared DNA we have with these relatives. The numbers are generally reported as being an average – meaning the possible ranges can be from 0% to twice the average rate. Generally, as averages go, the numbers will fall somewhere toward the middle of the continuum.

Degree of
Relationship
Shared Genetic
Material
Relationship
0100% Exactly  Identical Twins
150% Exactly  Parents
  Children
150% Average  Full Siblings
225% Average  Half Siblings
  Grandparents
  Grandchildren
  Full Aunts and Uncles
  Full Nieces and Nephews
  Double Cousins
312.5% Average  First cousins
  Half aunts and uncles
  Half nieces and nephews
  Great grandparents
  Great grandchildren
  Full great aunts and uncles
  Full great nieces and nephews
46.25% Average  Half first cousins
  Double second cousins
  Great great grandparents
  Great great grandchildren
  Great great aunts and uncles
  Great great nieces and nephews
  First cousin, once removed
  Half great aunts and uncles
  Half great nieces and nephews
53.13% Average  Full Second cousins
  Full First cousin, twice removed
  Half First cousin, once removed
  Half great great aunts and uncles
  Half great great nieces and nephews
  3rd great grandparents
  3rd great grandchildren
  Full 3rd great aunts and uncles
  Full 3rd great nieces and nephews

When looking at the above table, the amount of shared DNA between full first cousins is on average 12.5% - meaning that two first cousins may share anywhere between 0 and 25% of the same DNA. Is this enough to cause a problem? In most cases, no; however, where there have been genetic defects – these may be intensified. These run the gamut from the visible (syndactylism, polydactylism, dwarfism, albinism, and etc.) to the invisible (hemophilia and other health disorders).

Because of the interrelatedness of the crown heads of Europe, hemophilia plagued the royal houses into the twentieth century. With defective genes occurring in both parents, the chance of having genetic disorders increases. The textbook example of “pedigree collapse” causing health issues is the case of Charles II of Spain.

  Generations   Ancestors
  no pedigree collapse  
  Ancestors 
Charles II
122
244
386
41610
53210
66418
712832
Total25482

Charles was plagued by poor health and was characterized as being short, frail, epileptic, senile, and completely bald by the age of 35. He also was sterile, and his inability to produce an heir provoked the War of Spanish Succession two years following his death in 1700. The problems that plagued Charles II and other European royals is the fact that the gene pool was stagnated by so many intermarriages.

While the gene pool was not as stagnated as in Charles II's case, I know of one community in Pennsylvania and one in West Virginia where nearly all of the residents are genetically connected going back four or five generations.   In the West Virginia situation, there is a high incident rate of cancer and in the Pennsylvania example, a high rate of heart disease has plagued many of the residents.  

I guess the best example of this are the problems that occur with the selective breeding of animals.  A dog is a dog, but by selective breeding over generations and even centuries has produced a great variety of breeds where a collie, chow, borzoi, and Newfoundland are all different.  This is not unlike our ancestors who were isolated from others and certain characteristics were common to specific populations that led to physical differences that make full-blooded Swedes, Nigerians, Navajos, Chinese, Dravidians, Australian Aborigines, and Berbers all different in some manner or fashion.

Like with animal husbandry, certain populations may have a high rate of specific health issues that are endemic to a race or ethnicity.  Some of the more widely known include ethnic related health issues include the following:  Tay-Sachs disease among Ashkenazi Jews and Cajuns and Sickle Cell disease in descendants sub-Saharan Africans.

Although humans have self-selected mates over the centuries, good and bad genetic material has been passed down to descendants.  I am not saying that any specific race or ethnicity is better than others; I am saying that a stagnation of the gene pool due to isolation has produced not only distinct physical characteristics, but also has prolongated certain health issues.

So Marrying Your Cousin Is Bad


Early on in this discourse, I discussed the stigma associate with intermarriage of relatives. Much of this has been popularized by real stories of genetic disorders, but isolated consanguineous marriages may only carry a slight risk.

You may be able to go back several generations to find such marriages in your family. On my mother’s side, her grandparents were related. Both had mothers named Myers and we know that a family connection existed – the exact relationship has not been proven as of yet. We do know that they were not first cousins. I had been leaning toward the two being second cousins, however, after further research, I am supposing that they were actually second cousins, once removed. This would make the relationship of the sixth degree; on average, the two would have only shared 1.66% of their DNA.

My second great-grandmother Gardner on my father’s side was the daughter of second cousins who both had the same Gardner great grandparents. She married a half fifth cousin, once removed – who was descended from the first Gardner/Gardiner progenitor in the region. The shared DNA between her and her husband, however, was probably no more similar than a random sampled person in the general population.

A similar fifth cousin, once removed marriage occurred between our 32nd president, Franklin Delano Roosevelt and his wife Eleanor, the niece of the 26th president, Theodore Roosevelt. Although they shared surnames, the relationship was distant at best. Franklin's fourth great grandparents were Eleanor's fifth great grandparents.

That Was Then - What About Now


Does it happen in modern America? Certainly; in most jurisdictions there is no prohibition to cousins marrying. In all 50 states and the District of Columbia, second cousins are permitted to marry. In fact, 20 states and the District of Columbia permit marriages between first cousins.

The number of states that prohibit first cousin marriages between blood relatives is 19. Three of these states will permit marriage between adopted first cousins, but not genetic first cousins. Of the remaining 11 states, one permits marriages between first cousins, once removed; four permit half cousin marriages; five allow first cousins to marry under certain conditions; and Arizona allows first cousin marriages under certain conditions and marriages between half cousins.


One thing that I thought was interesting is that the five states that are generally considered to be America’s poorest states do not permit first cousin marriages. Often Arkansas, Kentucky, Louisiana, Mississippi, and West Virginia are the brunt of jokes concerning inbreeding; however, first cousin marriages are illegal in these states, whereas, it is legal in the more cosmopolitan states of New York, California, and Massachusetts.

Although I am not an advocate for marrying one’s cousin, the reality is that this has happened in the past, it is legal in a majority of the US, and the real danger comes when the available gene pool becomes diluted.

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