When I first began creating my family tree online a decade or so ago, I made the decision to include the in-laws of many of my cousins’, aunts’ and uncles’ families when they popped up during research.

Perhaps it’s the historian in me. Who knows?

Now, while tracing back many ancestors from the 1700’s and older. I’m glad I did, because of this little thing called “pedigree collapse”. In other words, it’s when two people, who have common ancestors reproduce causing there to be fewer ancestors for their descendants.

Today, this practice is generally frowned upon even when very little DNA is shared. For example, between a potential couple who may be fourth cousins. They share third-great-grandparents. To be honest, from what I’ve been seeing, most people don’t know who their third-great-grandparents were but their descendants will come up in DNA results and be part of the branches on the family tree.

Royal families are experts at “endogamy” which keeps the family wealth, etc. in the family. Small villages and no transportation also limited the dating pool so people married cousins. It simply happened and you can’t change history.

Back to my original point… When researching ancestors of a famous distant cousin of mine (for sport), I noticed that the same family names popped up through the nine generations, so it was good to reveal at least some of the in-laws along the way to see if there was more pedigree collapse along the way, up until the time when a few branches of that family left Germany and started a colony, now referred to as the Pennsylvania Dutch Community.