Sometimes I'll be staring at a record of a long-past ancestor of mine, and I'll suddenly realize, "This record makes no sense at all."
That happens when I see a many times great-grandmother has died age 311 years old. Or a great-grandfather has married someone after his death date. Or the people in the record are living in the mid-seventeen-hundreds, and along comes their close relatives suddenly living in the late eighteen hundreds.
Oh, there are so many ways to create a disaster instead of creating a family tree, that I occasionally wonder how any of us get it right.
But, get it right we can and do, if we only have a dash of humility - and pause to do verification checks on our work. Most programs will run an errors report, tattling on us when we make such egregious mistakes.
The mistakes that are much harder to spot are like when "everyone's tree" agrees that Mary Weld married Daniel Harris in 1648 and their son Thomas Harris Jr. is the father of the Harris line in New Jersey, migrating there from Connecticut.
The problem with that scenario is this: the records show that particular Thomas Harris married twice, had only one child, a daughter, and she died young and unwed. So we need a different Thomas Harris (or a different "somebody") to father the New Jersey Harris line of the late sixteen hundreds.
Conveniently, there is another Thomas Harris and he is a very different kettle of fish, as they say. Whether or not he is the particular person I'm searching for? More documentation needed to tell.
I cannot say this strongly enough in summary: consider all the hours of work, the expense and effort we go to in creating our family trees. When just a little more research will prove that we have our own ancestors perching on our branches, and that we haven't poached the ancestors belonging to someone else entirely, there is little justification for not taking the time and care to do so.