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Quantitative Genetics

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Interesting piece in The Wall Street Journal, which could have been cribbed from David Epstein's The Sports Gene (a very good book I might add), NBA Basketball Runs in the Family (if you go to Google News and search for the title it should come up and you can get a free copy): As indicated... Read More
This year at ASHG one of the most fascinating talks was Po-Ru Loh's, where he reviewed the BOLT-REML method. It's introduced in the paper, Contrasting genetic architectures of schizophrenia and other complex diseases using fast variance-components analysis. As you likely know many diseases such as schizophrenia manifest as complex trait; that is, they're basically quantitative... Read More
The above figure is from a paper in Proceedings B which shows a Dutch data set from right after World War 2. Controlling for several variables taller men and average height women have maximal fertility. The authors contrast the results from the United States, where it seems that shorter women and average height men have... Read More
IBD plays a big part in my understanding of inheritance. I don't mean inflammatory bowel disease. Nor do I mean isolation by distance. I'm talking identity by descent. Assuming your parents are "unrelated" then you are identical by descent with your sibling across some portion of your genome. You inherit identical segments from your parents,... Read More
Modern evolutionary genetics owes its origins to a series of intellectual debates around the turn of the 20th century. Much of this is outlined in Will Provines' The Origins of Theoretical Population Genetics, though a biography of Francis Galton will do just as well. In short what happened is that during this period there were... Read More
In part, genes. Luke Jostins reported this from a conference last year, so not too surprising. Evidence of widespread selection on standing variation in Europe at height-associated SNPs. Let me jump to the summary: In summary, we have provided an empirical example of widespread weak selection on standing variation. We observed genetic differences using multiple... Read More
According to the reader survey 88 percent said they understood what heritability was. But only 34 percent understood the concept of additive genetic variance. For the purposes of this weblog it highlights that most people don't understand heritability, but rather heritability. The former is the technical definition of heritability which I use on this weblog,... Read More
That's the question a commenter poses, albeit with skepticism. First, the background here. New England was a peculiar society for various demographic reasons. In the early 17th century there was a mass migration of Puritan Protestants from England to the colonies which later became New England because of their religious dissent from the manner in... Read More
The Pith: Even traits where most of the variation you see around you is controlled by genes still exhibit a lot of variation within families. That's why there are siblings of very different heights or intellectual aptitudes. In a post below I played fast and loose with the term correlation and caused some confusion. Correlation... Read More
In earlier discussions I've been skeptical of the idea of "designer babies" for many traits which we may find of interest in terms of selection. For example, intelligence and height. Why? Because variation on these traits seems highly polygenic and widely distributed across the genome. Unlike cystic fibrosis (Mendelian recessive) or blue eye color (quasi-Mendelian... Read More
In response to comments and queries below I've been poking around for more experimental material on quantitative genetics, and in particular the breeder's equation. That's how I stumbled upon this very interesting and informative obituary of D. S. Falconer in Genetics. It reviews not only the biographical details of Falconer's life, but much of his... Read More
In the comments below a reader asks about the empirical difference in heights between siblings. I went looking...and I have to say that the data isn't that easy to find, people are more interested in the deeper inferences on can make from the resemblances than the descriptive first-order data itself. But here's one source I... Read More
Kobe Bryant is an exceptional professional basketball player. His father was a "journeyman". Similarly, Barry Bonds and Ken Griffey Jr. both surpassed their fathers as baseball players. Both of Archie Manning's sons are superior quarterbacks in relation to their father. This is not entirely surprising. Though there is a correlation between parent and offspring in... Read More
I have discussed the reality that many areas of psychology are susceptible enough to false positives that the ideological preferences of the researchers come to the fore. CBC Radio contacted me after that post, and I asked them to consider that in 1960 psychologists discussed the behavior of homosexuality as if it was a pathology.... Read More
The Pith: When it comes to the final outcome of a largely biologically specified trait like human height it looks as if it isn't just the genes your parents give you that matters. Rather, the relationship of their genes also counts. The more dissimilar they are genetically, the taller you are likely to be (all... Read More
Aka Pygmies The Pith: There has been a long running argument whether Pygmies in Africa are short due to "nurture" or "nature." It turns out that non-Pygmies with more Pygmy ancestry are shorter and Pygmies with more non-Pygmy ancestry are taller. That points to nature. In terms of how one conceptualizes the relationship of variation... Read More
The Pith: In this post I examine how looking at genomic data can clarify exactly how closely related siblings really are, instead of just assuming that they're about 50% similar. I contrast this randomness among siblings to the hard & fast deterministic nature of of parent-child inheritance. Additionally, I detail how the idealized spare concepts... Read More
Two of the main avenues of research which I track rather closely in this space are genome-wide association studies (GWAS), which attempt to establish a connection between a trait/disease and particular genetic markers, and inquiries into the evolutionary parameters which shape the structure of variation within the human genome. Often with specific relation to a... Read More
In a nation of ~1 billion, even one where a large minority are positively malnourished, you'd expect some really tall people. So not that surprising: NBA Awaits Satnam From India, So Big and Athletic at 14: Punjab is one of India's more prosperous states. Interestingly this kid's paternal grandmother is as tall in standard deviation... Read More
In the early 20th century there was a rather strange (in hindsight) debate between two groups of biological scientists attempting to understand the basis of inheritance and its relationship to evolutionary processes. The two factions were the biometricians and Mendelians. As indicated by their appellation the Mendelians were partisans of the model of inheritance formulated... Read More
A major issue in human genomics over the past few years has been the case of the "missing heritability". Roughly, we know that for many traits, such as height, most of the variation in the trait within the population is controlled by variation in the genes of the population. The height of your parents is... Read More
I knew that Yao Ming's parents are very tall. Though his father, at 6'7, arguably contributed less than his mother, at 6'3, which is farther above the female mean in standard deviation units. But check this out from Superfusion: How China and America Became One Economy and Why the World's Prosperity Depends on It: What's... Read More
Razib Khan
About Razib Khan

"I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. If you want to know more, see the links at"