Saturday, January 2, 2016

Loss of ancestors - pedigree collapse

This post is not only Czech genealogy, but common basics - but I had a need to write it. It's focused on loss of ancestors, ie. the ancestors paradox or pedigree collapse. That's situation when you "loose" number of ancestors due to fact that related people marry. An excellent article about how everyone on Earth is related brought this topic to my attention.

I have found number of such cases during my career and I will use one of them as an example. I even have such cases in my own family but as it affects living people (it's case from beginning of 20th century) I can't use it publicly. Anyway... What exactly loss of ancestors is? How it happened? What were the reasons for marrying a relative? And how was is prevented? 

What is loss of ancestors? 
It's a situation when related couple married and therefor their descendants have less ancestors than they should have. Married couple could be first cousins, they could be really distant ones, but still related somewhere in deep history. 

If first cousins marry, it means two of their parents were siblings. And it means two of their parents have same parents. Which causes situation when child of first cousins has only three pairs of great-grandparents (ie. 6 people), not four. And only six sets of great-great-grandparents instead of eight (ie. 12 people). And only twelve pairs of great-great-great-grandparents instead of 16 (ie. 24 people instead of 32). And so on. 

Example of pedigree collapse - Františka Světlíková and Jan Světlík were siblings, their grandchildren Karel Kališ and Julie Zoufalá married. It means child of Karel and Julie had 4 grandparents, 8 great-grandparents, but only 14 great-great-grandparents.

How it happened?
Well. People married in close surroundings. They weren't travelling tens of kilometers (or miles) to find a bride or groom. So the risk they will married someone related was quite high. Normal radius to find a bride or groom was 5 kilometers (3 miles) which usually covered villages in one or two parishes. 

Larger concentration of married relatives was also in areas which were geographically separated from the rest of the country. This meant quite large parts of Bohemia and Moravia as there were many mountains there. And many people emigrated from these mountains because living conditions were too tough there and America promised much more. So if your ancestors came from some hilly area (such as Beskyds, Krkonoše, Šumava etc.) the possibility your ancestors were related is higher than in case of families from other parts of Bohemia and Moravia.

People often knew they were distantly related - the church even created family trees when there was suspicion a couple could be related. I have found such family trees in Skuhrov (Havlíčkův Brod district) parish archives: 

What were the reasons for marrying a relative?
Love? :) Well, that could have been one of the reasons, but there were more. I have already mentioned that people married people from their surroundings and were not used to search for a partner in larger distance from home. 

Another reason was wealth and property - people tried to keep it in one family so parents could force cousins to marry for such purpose. This was mainly the case of wealthier families, not the poor ones.

Another reason - pregnancy of bride. If a girl became pregnant with her cousin, they were forced to marry even against the common will of the church. They needed special dispensation from the church, for first cousins directly from the pope (or pope's nuntio in the country). In case of second cousins they needed dispensation from the archbishop.

And how was is prevented?
Basic tool to prevent marriages of relatives were marriage bans. Those were held in church during public masses on three festive days (feast or Sundays) before the marriage. The priest announced who is willing to get married and also asked the public to bring out any information why they couldn't marry. Fact groom and bride were related was one of the most common obstacles against the marriage. 

If they were related they needed special license as I already mentioned. And this license was not cheap, they had to pay quite a lot of money to get it. This fact also prevented marriage of close relatives because not everyone was rich enough to be able to pay the fee. 

And of course our ancestors knew that disabled people time to time came from marriages of close relatives - not so often as in case of noble families, but still there was a risk... And they tried to prevent such cases because taking care for disabled was much more demanding than today. 

So - do you have some cases of pedigree collapse/loss of ancestors?


  1. Did military service, journeymen, and religious pilgrimages help mix the local gene pool? I know I have one ancestor that married during journeyman service (he was from near Kutna Hora, his wife from Dvur Kralove, they returned to Kutna Hora). Thanks, love your blog.


    1. Yes, they helped. And of course foreign armies - as Czech lands are in the middle of Europe, most wars brought new blood to the region, which was quite important from the point of health of local population. We are often called "boiling cauldron" of Europe as all genes are mixed here. :)

  2. How closely might people have known they were related? How likely would my great-grandfather have known my great-grandmother was his 4th cousin; or would his sister have known she was marrying her 6th cousin? Or was marriage beyond 2nd cousin not restricted? Of course the more distant the relationship, the less chance of genetic inbreeding problems. But these people lived in such close proximity for many hundreds or more of years, they had to be all related in some fashion!

    1. They all were related in some fashion. :) But they were often not aware about it. Even people with the same surname who had the same ancestors 100 years ago was convinced they were not related at all (and they still are as my experience from field research says).

      There were several grades of relations, 2nd grade were 1st cousins, 3rd grade 2nd cousins, 4th grade 3rd cousins (with some exceptions, I will write a blog post about it) - the rest was not restricted.

  3. Despite a collapsing pedigree, I've still found less of that happening with my Czech ancestors than with some of my English colonial ones. Still, I'm sure it was a good day for the gene pool when my Czech and English sides got together! :)

    Also, I appreciate it when the record lists to what degree the couple was related. Sometimes if I'm stuck on one line, it's nice to know who another descendant is, so I can try to follow up a different ladder to the same common ancestor.

  4. I have also seen this in my ancestry. However, the 2nd cousins married after they had individually immigrated to the U.S from Bohemia. Also, my husband's French Canadian ancestry is really full of these types of relatives marrying. Haven't seen any 1st cousins so far though.

  5. Yes, I have a situation where a brother & sister had Great Grandchildren married to each other. I was shocked when I found that the the Judith Pallas' were the same person on two different lines of the same tree!!

  6. I am looking for information about Vsetin, Hostalkova,North Moravia. Looking for marriage,birth,christening,and death records.

  7. My grandfathers oldest brother married his 3rd cousin. Their daughter told me the family never knew this - at least, not until I uncovered it. :)

  8. my maternal great-grandfather married all 3 sisters of the same family - his first wife (Magdalena) died of childbed fever after the birth of her 3rd child (my grandmother); his second wife (Marie) died of burns after having 2 children and the last sister (don't know the name) outlived him (no children). I've never been quite sure how to describe the relationship of the five children born to 2 of the sisters he married - half siblings?