Relying on other peoples’ family trees

I found a fun video from Family History Fanatics listing seven common genealogy mistakes. I’ve made every single one of these mistakes, and developed some guidelines for avoiding them.

The third mistake is relying on other people’s trees, and here are my principles for how I make use of other trees on,, etc.

I group all genealogical sources into three types: Primary, Secondary and Tertiary. Primary source documents are created contemporaneously with a given event.

Secondary source documents are detailed analyses written after the event—sometimes centuries after—and are based on explicitly cited primary source documents.

Tertiary sources are summaries of family research without supporting citations.

Family trees on the web could be either secondary or tertiary sources, but you should handle them exactly the same way:

  • Don’t cite other trees, use them as roadmaps to do your own research.
  • When choosing a roadmap, look for ancestor profiles with unique contributions and high fact counts.
  • Be careful who you trust: a high-quality researcher may not have high quality research throughout their tree.
  • A DNA match doesn’t prove your paper trail.

First, the person who created the tree had good intentions. They’re not lying, they’re not fabricating facts out of thin air. They want to get this right. But they’re human, and they make honest mistakes. One confusing record could have led them to jump to conclusions, and the end result is an erroneous tree. Point is, examine their research, use it as a roadmap. If they did it right, you can speed up your work substantially. And if they made a mistake, maybe you can catch it.

Second, you’ll probably find a bunch of profiles for your ancestor. Most of them will be nearly identical, because people often just copy from other trees and move on. So just pick one tree profile as a roadmap. I prefer profiles that have high source count, assuming they are primary sources. If I see lots of millennium file and American genealogical biographical index records, I move on. If I see the genealogist added scanned images of probate files or other primary source documents, that makes me feel I’ve got a solid roadmap.

Third, once you’ve dug into your own tree pretty deeply, you’ll find other researchers who consistently land quality work. Michelle Fury and Dan Perry are my favorites for my mother’s family, and I hope others have come to rely on my research into the Slough family in the 1700s and 1800s. Thing is, I know that my quality research only applies to specific people and lines in my tree. Other parts of my tree? Not so much. Lots of fact copying with little more than census records and find-a-grave sources. Point is, even when you trust the researcher, you should examine their work on each profile.

Final point, I see a lot of people claim that their written-record-based genealogy is “confirmed by DNA” when they get a DNA match to someone else with the same written-record-based genealogy. But you could both have the exact same error in your trees.

For example, I have this one family in my wife’s tree that sprouted from a single guy in Jamestown, John Chew. Everyone has a record-based lineage that connects my wife’s tree to John’s youngest son, but… the DNA matches before a particular generation (about 1800) were all to people descending from the eldest son. Turns out the record-based lineage might be wrong because in 1820, my wife’s fifth great uncle, Joseph Chew married a woman named Emily Chew, and the record-based lineage was completely dependent on the assumption that Emily’s maiden name was not Chew at all. Whoa.

You could also have a false positive—whether it’s via a genetically isolated community sharing common indicators, or just by chance.  And… let’s get real, hanky-panky wasn’t invented in the past one hundred years. People have been sleeping around since before some human came up with the idea of marriage. I keep looking at my wife’s paternal DNA matches, and can’t find a single tree/DNA match past her third great-grandfather.  DNA matches are not infallible evidence of a paper-and-pencil lineage.

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