The software application I use to keep track of my ancestors is able to produce many different graphical charts to help visualize “who begat whom”. Based on the Ahnentafel (Ancestor Table) numbering system, the traditional Pedigree Chart of boxes connected by lines is probably still the most useful and understandable. But the so-called “Fan Chart”, although less legible beyond 10 generations, is more appealing graphically and is almost a genealogical icon of an individual.
Human genetic inheritance, like computers is based on a binary numeral system. Each of us inherits half of our genes from each of our two parents. The double or 360º fan chart illustrates our binary genetic history through time. The starting person, generation #1, occupies the centre of chart. Each ring, from the centre to the periphery of the “fan” represents a generation. Inividual> Parents> Grand Parents> Great grandparents> Great great grandparents> etc. or Generation #1> Generation #2> Generation#3> Generation#4> Generation#5> etc. Each generational ring is occupied by twice as many individuals as the adjacent inner ring so 1 individual> 2 parents> 4 grandparents> 8 great grandparents> 16 great great grandparents. The outer ring of a 10 generation fan chart would contain 512 GGGGGGG grandparents. The number of individuals in a 10 generation fan chart would total (1+2+4+8+16+32+64+128+256+512) or 1023. This pattern of doubling numbers every generation is familiar to both genealogy and computer nerds.
A generation is the average number of years between the birth of parents and the birth of their first offspring. This number varies through history, cultures, families and gender. For my genealogical research I assume 25 years as a generation. I’m a “baby boomer” born about 1950. My parent’s generation would have been born about 1925 and my grandparents generation would have been born about 1900. If I count back ten generations to my 7X Great Grandparents I estimate they would have been born about 1700.
It is possible to have members of a family from 4 generations living concurrently and occasionally a “living memory” can be passed from a Great Grandparent to a Great Grandchild. But beyond 4 generations a genealogist must rely on stories (family knowledge) or documents to tell them about their ancestors. From my fan chart below you can see that the first 4 rings outside my circle have no gaps. This means that I know at least some basic information about all 16 of my great-great grandparents who I estimate were born about 1850. Although it took me a few years to uncover this information it was relatively easy to do with online research because civil registration of births, marriages and deaths (BMD) as well as census enumerations more or less began at least in some parts of the United Kingdom and Canada in about 1840. There are other records that have been indexed and digitized from before this time but these are mostly church records and not as easy to find or interpret. So the farther out the circle goes the more gaps in knowledge there are and the more irregular the fan becomes. It’s not feasible or even much fun trying to fill in one ring completely before moving on to the next. I, like many amateurs, put my initial efforts into tracing my paternal lineage back as far as possible because in our culture that is how our surnames are passed down the generations.
And so now it’s a race against time… how many more rings can I fill in before I, and my ancestral history are floating around like so many binary numbers in the ethosphere?
Ancestors of my paternal grandfather, Stephen Peers.
Ancestors of my paternal grandmother, Sarah Upton.
Ancestors of my maternal grandmother, Jessie Margaret Dodd.
Ancestors of my maternal grandfather, Howard Clayton Smith.