Sometimes when I take a serious look at one of these online trees, I find dates, children, or other information that I had been seeking. Because someone cited their sources with that online tree, I also learn about new places to look for my family's history. Other times, I find information that seems to be incorrect - a reversed order of names for my Grandmother Myren, children born years after the death of their father, very different birth or death dates, the list goes on. Then I'm left wondering what to do with such differences in information or questionable data.
When I come across an online family tree with new or questionable information, rather than immediately adding the information to my family tree, I print out the new data and keep it in a "Check On" folder. Later, I will look further into the information that has citations, sometimes finding new data that I will add and cite in my family tree.
If the only source for information on an online tree is another online tree whose source is another online tree ..., I personally look at this as unsourced data because I have no idea where it originally came from. No source means that my confidence in using that information is greatly diminished. Instead, I will use the unsourced information to develop new research goals for my personal research. Then, when I find sources to validate this new information, I can add it to my tree with confidence (and source citations). I'm not trying to reinvent the wheel, but I want to be sure that what I share about my family is accurate, not conjecture or unsubstantiated information.
The authors of The Official Guide to rootsweb.com have this to say about online family trees:
Even Ancestry.com has a similar caveat relating to its Public Member Trees:This information is provided by individual submitters. Evaluation of the accuracy of the information is left up to you. ... [It] only provides clues and contacts for your further research - not proof of a pedigree or a family history.
These trees are voluntarily submitted by Ancestry users like you. We take all tree data "as is" and cannot guarantee the completeness, accuracy, or timeliness of the information contained in this database.It is worth remembering as we look at shaking Ancestry leaves or other online family trees that they can be a start but not the end of our research.