I decided to write this blog post to accompany my appearance on the Insight Podcast, where I talked about heritability, how much of it is ‘missing’, and what the the recent preprint from Peter Visscher’s group has shown. Heritability is the fraction of trait variation in a population due to genetic inheritance (see here). As I … More Missing heritability revisited
If you see a headline that says ‘genetic variant linked to higher body mass index’, what that usually means is that, on average, people that have one version of a genetic variant (an ‘A’ letter in their DNA code, for example) have a higher BMI than those with the other version (a ‘T’ letter in … More Finding genetic effects on phenotypic variability
Whether resemblance between relatives is due to genes (nature) or environment (including nurture) has generated much controversy, especially for traits like education and intelligence. The modern scientific effort to disentangle nature and nurture can be traced, in large part, back to Charles Darwin’s cousin, Francis Galton. Prompted by Darwin’s theory of evolution by natural selection, … More Relatedness disequilibrium regression explained
I am writing this post to answer some of the reactions I got to my recent article on ‘Estimating heritability without environmental bias‘, in which I develop a novel method, RDR, to estimate heritability, and apply it to 14 human traits. RDR uses IBD segments to infer heritability. RDR therefore handles rare variants similarly to … More RDR and rare variants
In the first part of this series of blog posts, I gave my definition of heritability. I defined heritability as the fraction of trait variability explained by direct genetic effects alone. Direct genetic effects are the effect of genetic variants in a body on that body. They are distinguished from indirect genetic effects, which are … More Heritability estimation: the central problem (ii)
This post aims to define what heritability is. We define and estimate heritability so that we can measure the relative importance of genetic inheritance versus environment in explaining differences between individuals in a population. The relative importance of genetic inheritance (nature) versus environment (including nurture) for human traits has generated much controversy over the years. … More Heritability Estimation: what is heritability? (I)
In this post, we look at how a statistical interaction (Part I) between two genetic variants affects the correlations between relatives. An interaction between two independent SNPs can be written so as to give an orthogonal partition of the variance due to the interaction (Part V). If the genetic component of a trait, , is … More Interactions in Genetics VI: correlations between relatives
In this post, we look at how the genetic variance due to an interaction between two SNPs can be decomposed into additive and epistatic components. In the following post, we will look at how these variance components affect the correlations between relatives. It is important to realise that the component of the variance due purely … More Interactions in Genetics V: variance components
In this post, we see how we can go from the probability that two individuals share alleles by descent from a common ancestor, identity-by-descent sharing (IBD), to correlations between their genotypes. This is the foundation of how we go from relatedness between individuals, which can be encoded in a pedigree, to correlations between their traits, … More The relationship between identity-by-descent (IBD) sharing and genetic correlation
The invention of cheap genotyping arrays allowed for the collection of samples of thousands of individuals with both genome-wide genotype data and phenotype data, enabling an unprecedented rate of discovery of genetic variants associated with human traits and diseases (Visscher2012). The amount of variance explained by the additive effects of discovered loci is currently only … More Interactions in Genetics IV: missing heritability.
geneticvariance.wordpress.com 