Samples epistatic effects from a normal distribution or gamma distribution with a variance relative to the variance of the additive effects
sampEpiEff(qtlLoci, nTraits, corr, gamma, shape, relVar)a matrix with dimensions qtlLoci by nTraits
total number of loci
number of traits
correlation between epistatic effects
indicator of trait should use a gamma distribution
gamma distribution shape parameter
desired variance for epistatic effects