Apparent when examining family groups, village life in past centuries inspired complex genetic interlinking. Difficult to chart are when siblings from one family marry siblings from another. We must see this to understand it best.
Double Relatives Explained
Captivated by “ancestor loss,” I search for those who can visually explain it, but I come up with very little. It is surprising to find a topic so unexplored, yet so pervasive.
I submit that anyone descended from villagers, anywhere in the world, will confront genealogical confusion. Since the world was primarily agricultural until about two hundred years ago, this does include everyone!
I discovered this phenomena of genetic narrowing by surprise. Knowing that my grandmother’s two grandmothers were first cousins was a hint—but it was simply a family amusement. Now I find that this was a major and common social/genetic phenomena that few have written about, maybe because it takes study of siblings to understand and most researchers concentrate only on direct-line ancestry.
Another problem with “ancestor loss” is that we do not have words for these relationships in English. Other than “double first cousins,” I have found little or nothing about how to approach such a tightly woven social fabric. (To research means wading through the information about when a sibling marries a sibling—a brother marries his sister—but that is rare. Not incest, what is studied here is pervasive in village life—two brothers marry two sisters.)
If species improve through diversity, the past was a problem. It appears that my grandparents’ genetics were not very diverse. With the scant photographs that come down to us, they also all looked similar. (The family has always been astounded how my brother looks EXACTLY like a paternal great-grandfather! Recently, a third cousin I have never met sent her photo and she looks more like my sister than I do! (I genetically favor a different branch)).
As a visual professional, I can’t tolerate a visual mess. Any charts I have found that express these complex relationships (most evident in royal families) look like a plate of spaghetti. Then the records apply a percentage to this phenomena, such as Frederick the Great had 68% ancestor loss. How do they determine this? And when I analyze my very messy family tree, how can I better understand this?
So here is my graphic attempt at the sibling to sibling relationship. (More common were cousins marrying cousins. But there are as many cases of siblings marrying siblings, and on this I focus here.)
This socio-genetic tendency ended in my family only with my parent’s generation. They were the first to marry out of choice and their families were not related. Therefore, I am much more genetically diverse than either of them, or anyone back on the family tree. Today arranged marriages have disappeared in my society, though it continues in the world.
Analyzing ancestor loss, this chart demonstrates 50% for the resulting offspring of sibling pairs: instead of four sets of grandparents, there are two. Further, the children of these unions are more than cousins, and are genetically like siblings. By making this visual, the effects are immediately obvious.
Anyone delving into past centuries will find this phenomena. It should not be glossed over just because it is complicated. The implications of such a different custom of marriages and relationships is background to understanding the challenges and decisions of that time.
With this awareness, I look into the relationships of my own family and discover many of these pairings. My calculations of multiplying backwards (4 grandparents, 8 great-grandparents, 16 great-great-grandparents, etc.) must be revised. I have less ancestors than I thought. And rather than a direct line so cleanly expressed in today’s analytics, I am related to clusters of tightly-woven relationships that I wonder if even they could sort out! The term “cousin” had more nuances of meaning and levels in the past.
When first discovering this genetic mess, the blog I posted got 1,000 hits in one day! Obviously I hit a nerve. It is universal, yet understudied. I have just scratched the surface of implications but am looking for those who understand this better.
Only two generations ago, societies possessed little genetic diversity. Yet, the new generations are becoming genetically international! Tight communities have loosened up through immigrations, evolving from my generation, a nationally-based “melting pot,” to an international one. Nature proves genetic diversity increases the quality of a species, so future generations should be smarter, more talented, and healthier. Fingers crossed! But, at the same time, we need to preserve the cultures of our past, respecting the differences as we all become more alike.
—Always inspired, Liane
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Liane Sebastian wears an editor’s hat, designer’s coat, and artist’s shoes.