> For example, take the simple family tree above. If I’m person 28 on this family tree, and I’m making a genealogy, I would care about my own ancestors, but I might not care much about my ancestors’ siblings (my aunts and uncles) and their descendants. So most of the family tree won’t be present in a genealogy database
Or, the data is correct and a lot of lines of people just die out without offspring.
Or most people can't trace their lineage all the way back to 1809 and some ancestors just spawn into existence (or descend parthenogenetically from a single parent) at a later date.
Maybe those missing ancestors could be imputed by sampling a random other individual with known parents born in the same year.
I think that’s likely it. One should instead build the tree backwards starting with the most recent members of the database and then find their earliest known ancestors. These can then be assigned the magic trait based on the likelihood of it being present based on their birth year cohort (or more reasonably birth decade or some other larger bucket).
No, that can't explain his result showing the witch gene going extinct despite, by stipulation, zero fitness impact on individuals but 100% transmission. Because the human population did grow over that time, so every deadend must have been balanced out by even more children by the non-deadends. And since he starts at hefty fractions like '1% of the entire population' (and goes up to 20%), we should be well beyond any issues of very small number effects or gambler's ruin.
There has to be something wrong with either the data or code. (It almost looks like a sign error!)
The linkage file is probably missing a lot of linkages. As someone who has done some genealogy research, at a certain point you just start guessing based on last name, age, region and hope its right. There's also a big trend of people getting to a point where there are multiple options (similar names, ages, region) and picking the most well documented lineage to hook their genealogy on to.
Saying "magic" is wrong anyway, at least unless you did multiple tests with multiple genes, I'm not sure why you would expect magic to be Mendelian unless your only prior is Harry Potter, and even there dubiously.
The author's interest in middle-grade books is fascinating. I'd love to read a post of recommendations with accompanying rationale, if only to get ideas for books my daughter might like!
How I Live Now, by Meg Rossof, is a stellar novel. There are some really, really good books marketed as YA (Young Adult) (that's the term I know for what he's calling "middle-grade" - maybe that's new branding?), only because their protagonists are teenagers.
"Middle-grade" is the age category before "young adult" https://en.wikipedia.org/wiki/Middle_grade_fiction pragmatically because younger children aren't as interested in the topics that captivate hormone-filled teenagers.
I am ten books into the Wings of Fire series by Tui T Sutherland because my grand daughter likes it. My main reason for liking it is that it gives me a glimpse of the type of anxiety that young kids routinely go through. I think the main reason my granddaughter likes it is because of the dragons.
I really enjoyed Terry Pratchett’s YA books with Dodger and Nation being favourites. Maybe see if you can get access to the librarian at your kid’s school? They’ll be experts
Or, the data is correct and a lot of lines of people just die out without offspring.