November 8, 2019
A few weeks ago when Judy Russell was in town for our C4aC, she mentioned that she loves “long generations.” That started me thinking about exactly what constitutes a “long” generation. Generation length varies across time and between different families, but genealogists often use a rough number of between 25 to 30 years per generation as a guide. Although these numbers are not exact, they can be helpful when evaluating whether there are too many or too few generations on a given pedigree chart. For example, a chart showing only three generations between a man born in 1980 and an ancestor born in 1775 is probably lacking a few generations. Similarly, a chart showing five generations between that same person born in 1980 and an ancestor born in 1890 needs to be examined carefully to make sure that a two-year old girl isn’t shown as giving birth.
Families vary in their generation length, with some having shorter and others having longer generations, but, for most, the short generations balance out with the longer ones. That’s in the long run, but in the short run, genealogists like those long generations because they mean that someone living today is more closely related to someone who lived long ago. In my own family, I have a cousin (FTM says she’s my second cousin, twice removed) whose grandfather was the younger brother of my second great grandfather. When I first met her and she explained how we were related, I thought she’d made a mistake and omitted a generation because my second great grandfather was born in 1832, and her grandfather, his younger brother, was born in 1838. It seemed impossible that her grandfather could have been old enough to serve in the Civil War and still have grandchildren only a few years older than I am. As it turns out, my cousin comes from a line of long generations. She was born in 1935, when her father was 51 years old. Her father was born when his father was 46 years old, making my cousin’s grandfather 97 years older than she. In contrast, my grandmother on this same line was 58 years older than I am, making for much shorter generations on my line.
Although my cousin comes from a line of long generations, there are cases of even longer generations among the first families of the United States. Tenth president of the United States John Tyler was born in 1790. His son Lyon Tyler was born when John Tyler was 63 years old, and Lyon Tyler had a son born in 1928. Lyon was 75 years old at the time, and his son Harris is still alive, meaning that, as of 2018, a man born in 1790 still had living grandchildren. Although John Tyler is the most famous example of long generations, there are undoubtedly more families whose long generations just haven’t been documented.
Besides being interesting to ponder, long generations can have significance for tracing family trees, particularly when it comes to DNA. The most recent common ancestors for my cousin and I are my third great grandparents, but those same ancestors are only her great grandparents. That means that I probably inherited about 3.125% of each of those ancestor’s DNA, while my cousin has nearly four times as much DNA from them at about 12.5%. Having access to that much more DNA from an ancestor is a good reason to try to locate and hopefully test a long generation cousin. Of course, getting to know someone with such an interesting pedigree is also a great bonus.
Researcher/Director at Large