The following is a Plus Edition article written by and copyright by Dick Eastman.
Are you confident of the accuracy of your genealogy data? You might be amazed at how many databases I see that include mothers giving birth at the age of three, marriages at age twelve, or deaths at the age of 135. Sometimes you even find a person with a birth date prior to those of his parents. Download almost any GEDCOM file from the Internet and I suspect you can find similar problems.
Such errors are easy to create. Sometimes selecting the wrong person in original records can cause such errors. Copying someone else’s errors can cause other errors. Mistakes also occur because you had a keystroke error when entering the data; attempting to type 1835 on the keyboard can easily result in 1845 being pressed on the keys.