Sibling design or bust for polygenic risk scores
Unless you have been sleeping under a rock you are aware that there are lots of constant discussions about “polygenic risk scores” (PRS) and residual “population stratification.” The basic issue here is that when you have a risk profile generated by lots of smaller genetic effects that you sum up together the inference of those […]
The arc of selection on polygenic traits
A very important new preprint, Polygenic adaptation after a sudden change in environment: Polygenic adaptation in response to selection on quantitative traits is thought to be ubiquitous in humans and other species, yet this mode of adaptation remains poorly understood. We investigate the dynamics of this process, assuming that a sudden change in environment shifts […]
Not happening at genomic speed: diversification of GWAS panels
One of the things that is evident and the norm when you are interested in genetics and genomics is that things happen fast. There are some sciences which proceed at a normal and conventional pace. But, because genomics is fundamentally driven by the …
Soft & hard selection vs. soft & hard sweeps
When I was talking to Matt Hahn I made a pretty stupid semantic flub, confusing “soft selection” with “soft sweeps.” Matt pointed out that soft/hard selection were terms more appropriate to quantitative genetics rather than population genomics. His viewpoint is defensible, though going back into the literature on soft/selection, e.g., Soft and hard selection revisited, […]
Why northern Europeans are taller than southern Europeans?
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 empir…
Most people don’t understand “heritability”
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, […]
Are genes the key to the Yankee Empire?
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 […]
How do relatives correlate in traits?
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 […]
How a “designer baby” might just work
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 […]
D. S. Falconer, 1913-2004
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 […]
How much do siblings differ in height?
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 […]
A mediocre man’s great son, a great man’s mediocre son
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 […]
On the real possibility of human differences
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. […]
Marry far and breed tall strong sons
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 diss…
Pygmies are short because nature made them so
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 …
Why siblings differ differently
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 de…
Of association & evolution
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 particular […]
The future Indian Yao Ming
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:
In a country of 1.3 billion people, 7-foot, 250-pound Satnam Singh Bhamar has become a beacon for basketball hope.
At age 14.
…
That […]
Genetics is One: Mendelism and quantitative traits
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 […]