Or better still, how good is the memory of the family member that you are interviewing? I can remember the funeral of John K. Kennedy around Thanksgiving, but what year was it? Did Aunt Mary die the same year, or what events do we use as the possible recall of family births, deaths, etc.? Sometimes a certain memory gets passed down through the generations. It could be the 1700s (not 1900s) that Aunt Mary married Abel Conner. This is why court house records are so important, because they document dates and events. Census records have a parallel memory, except it all comes from a census taker who wrote down what he was told, frequently spelling it to his own liking. Applications for pensions of various wars also have parallel memories, in that the applications themselves are based upon individual memories. Although a more accurate source, the information on tombstones comes from family memories during unpleasant circumstances. Yet, birth and death certificates are much more reliable, if the ancestor died during the era when such filings were recorded by law. Many unrecorded marriages occurred, simply because the minister was not required to file the license with the court house. Do you see how this goes?