format
Matrix with columns:
rlll{
[,1] affected numeric affection status (1=yes, 0=no)
[,3] attr numeric simulated quantitative attribute
[,5] M1.1 numeric the first allele of hypothetical SNP M1
[,6] M1.2 numeric the second allele of hypothetical SNP M1
[,5] M2.1 numeric the first allele of hypothetical SNP M2
[,6] M2.2 numeric the second allele of hypothetical SNP M2
[,7] M3.1 numeric the first allele of hypothetical SNP M3
[,8] M3.2 numeric the second allele of hypotetical SNP M3 }