For several years I have been exploring my family tree, building on the work of my maternal grandfather and my father who pieced toegether information they had into two branches of ancestors.
It is far easier now than when my grandfather did his research in the 1980s, and my dad did his in the mid 1990s. In those days you had to go to the sites where the records were preserved (Register Office, cemeteries, churches — for baptism, burial, and marriage records). Now, online websites, offer free or paid services that let you browse document collections online. Government offices have searchable data (census, weddings, births, deaths, migration, etc.)
So, building on the work of my predecessors, I have added more information and found interesting data about my family.
It also helped me put in perspective things like generation times, the size of families, the terrible mortality rates of past ages, and the effects of these factors on the genetic mixup that I carry.
Each generation dupicates my direct ancestors (two parents, four grandparents, eight great grandparents, sixteen great great grandparents, and so on), by the time you have gone back seven generations to, say, James Whitehall, born in 1741, you have 128 great great great great great grandparents. Each of them contributed genes to their offspring, but even though you'd reckon that you received 1/128th of their genetic material (or 0.78%), it is very likely that you did not get any!
This is because genetic material is sliced into chunks, and recombined. Although on average a child gets 50% of its genes from each parent it may not be exactly 50 percent because these chunks aren't equal. So, alleles are passed on in a random way. So as you go further back in time, the chances are that a given ancestor's genes may have got lost on their way to you. Below I quote Bird, 2025 to clarify this fact:
"For example, while each of a person's four grandparents is expected to contribute to 1/4th of their autosomal genome, ten generations (~250–300 years) ago, a person can have at most 210 = 1024 ancestors. Thus each of these more distant ancestors is expected to contribute to < 1/1000th of their autosomal genome, with a ∼58% chance of no detectable relationship at all. At fourteen generations ago (∼420 years), this probability goes up to <95% (Donnelly 1983; Ralph and Coop 2013). For this reason, our genome is necessarily only a snapshot of a fraction of a person's complete set of ancestors and carries no information about the ancestors that did not contribute any DNA to this particular descendant."
I am certain that my mother's mtDNA is in my body's cells, and that it came from her mother, and so forth, along that matrilineal line. But, many mothers' mtDNA never got a chance to pass on because they only had sons, their daughters dying before they managed to reproduce.
Regarding the man, I am also certain that I carry the Y chromosome along a patrilineal line which may or may not be that of those who passed on the Whittall surname given the proclivity to stray that we humans have when it comes to making babies. A study by Guerrini, 2022 published in Cell, found that "3% of the total sample learned that the person who they thought was their biological parent is not." So, who provided your Y chromosomes may not be too certain.
My X chromosome came from my mom, but... which of her two X chromosomes did I inherit? The one she got from her Dad, and therefore, originating in his mother, or the one that came from my maternal grandmother, which in turn could have come from either of her parents... Complexity increases as we move deeper into the past.
Regarding the autosomal DNA, I carry a cocktail of alleles in my chromosomes, passed down from past generations, but, as mentioned further up, some ancestors are not represented, and their signature has been lost. This is like a bottleneck. Genes got lost despite the fact that there is a continuous line of descent between those ancestors and me.
Generation times vary. For instance James Whitehall, is 7 generations from me, and this spans 218 years between our birth dates: 31.14 years per generation. Taking another random ancestor on my maternal line is James Paterson, born in 1781, seven generations away, 178 years, 25.42 years per generation. I didn't average all 128 ancestors of those seven generations ago, but as you can see, the spread is large; roughly 28 ± 3 years.
A study published in Science by Wang et al., 2023 found "an average generation time of 26.9 years across the past 250,000 years" which seems more or less similar to the one of my family tree. However, the paper states that "The average human generation interval was at a recent minimum of 24.9 ± 3.5 years at ~250 generations ago (6.4 ka ago), roughly concurrent with the historic rise of early civilizations. Before this, it had declined from a peak of 29.8 ± 4.1 years at ~1400 generations ago (38 ka ago), just before the beginning of the Last Glacial Maximum." So, bearing this in mind, my family seems to have a longer generation time, roughly 10% longer than this paper's value for the recent past.
Finally, I was surprised at how people died at a young age. Women bore children from age 20 to their mid 40s, as many as 14 children, and most died in their youth. Women and men lost their spouses and remarried in their 30s and 40s, some did so even twice! The world was deadly in those days before vaccines, antiseptics and antibiotics. These deaths also erased many genes that my distant cousins and great great uncles and auntes carried.
So, just looking back at my family, I wonder how can we be so certain about the genetic diversity of some populations, generation times, admixtures, bottlenecks, when chance and probabilities rule how genes are passed down from our distant ancestors, even in a healthy population in Modern Scotland, England, and Ireland.
Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2026 by Austin Whittall ©
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