There are thousands and thousands of compiled family histories. Many of these are surname books, tracing the descendants of a remote ancestor of the author or authors or tracing the pedigree of the author. Sometimes these books have both an ancestral pedigree of the remote ancestor and a list of all of the descendants. For example, if you look at the descendants of the Mayflower passengers who arrived in North America in 1620 in what is now Massachusetts, it is estimated that there may be as many as 35 million people worldwide who can claim ancestry to the Mayflower passengers.
It doesn't really matter if this is true or not, but I have met a number of people who were desperately trying to "prove" their relationship to the Mayflower or some Revolutionary soldier or even an Indian. The reasons for such efforts vary.
So what about compiled (i.e. printed in a book) genealogies? Unless your ancestor wrote his or her own history or autobiography, these sources are almost all derivative in nature. When looking at any derivative source is to evaluate the original source provided by the author and determine the reliability of the material.
There is a vast difference between say, the Five Generations Project books, also called the Silver books from the General Society of Mayflower Descendants and "John Doe and his family" by Richard Roe with no citations to any sources and obvious errors in places and dates. What I fear is that many researchers don't know the difference.
There are also cases where fraudulent genealogies were compiled such as Gustave Anjou who wrote dozens of books and compiled dozens of pedigrees for clients in the late 1800s and early 1900s. He was a fraud and charlatan and there were many others. This practice was so prevalent that almost any compiled genealogy is suspect. Even if the compiled genealogy pertaining to your ancestors was not fraudulent and came from a different time period, the author may have inadvertently included information from a fraudulently compiled earlier source. Compiling a fraudulent genealogy was often motivated by an expectation that the recipient would be connected to a claim against an estate in England or the rest of Europe. The bogus genealogists preyed upon the gullibility and greed of their clients, giving them what they expected rather than accurate, correctly documented pedigrees.
It is important to carefully document any claim in a compiled genealogy before accepting it merely because it is written in a book. However, as noted by the FamilySearch Research Wiki article, "Armchair historians, family-tree climbers, and professionals are all among the guilty. Many are well-meaning folk who "just got carried away" by imagination, enthusiasm, or inexperience."
So, here are some questions to ask about any surname or compiled genealogy book:
Surname books can be a treasure or a trap.
Written by James L. Tanner. Used with permission.
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