Simulate a single data set consisting of n subjects and 2 phenotypes for each
sim1(X, B, Vg, Ve, kinship)
design matrix (incorporating genotype probabilities from two loci), dn by df
a matrix of allele effects, f rows by d columns
a genetic covariance matrix, d by d
an error covariance matrix, d by d
a chromosome-specific kinship matrix, n by n