[3]var(y)=ZZ′σu2+Iσe2=ZZ′σg2m+Iσe2=Gσg2+Iσe2 where G is the genetic relationship matrix between pairs of individuals at causal loci. This equation shows the equivalence between the classical definition of heritability ( h2=σg2/σP2) with σP2 being the phenotypic variance, and the proportion of phenotypic variance explained by the causal variants altogether.
