# Changes

we use a variance component model to handle familial relationships. In a sample of n individuals, we model the observed phenotype vector ($\mathbf{y}$) as a sum of covariate effects (specified by a design matrix $\mathbf{X}$ and a vector of covariate effects $\boldsymbol{\beta}$), additive genetic effects (modeled in vector $\mathbf{g}$) and non-shared environmental effects (modeled in vector $\boldsymbol{\varepsilon}$). Thus the The null model is:
$\mathbf{y}=\mathbf{X}\boldsymbol{\beta} +\mathbf{g}+ \boldsymbol{\varepsilon}$