Do the tendency of multy Gene related illness follow normal distribution?

Answer 1

Most common multi gene diseases do not exhibit a clear pattern of heritability. So geneticists argue that the observed variations in susceptibility must be caused by the interactions among multiple polymorphisms. In such cases, individual polymorphisms are harmless, but when they occur in a specific combination they significantly enhance a person’s risk. In some cases, the increased susceptibility may be due to the collective action of a few polymorphisms, but in others they may arise from the subtle interactions among hundreds of gene-variants.
So the distribution can not be predicted on the basis of basic genetics