(i.e., offspring's uncle), met ND criteria (medium- genetic, low-environment (MG-LE) risk group). Offspring in the HG-LE group (group 2) are posited to have been at high genetic risk because their fathers share 100% of their genes with their ND cotwin, whereas those in the MG-LE (group 3) are at medium genetic risk because their fathers share on average 50% of their genetic material with their ND DZ cotwin. Both groups 2 and 3 offspring are posited to be at low family environmental risk because they were reared by an unaffected father. Finally, group 4 was comprised of offspring whose fathers and father's cotwin (MZ and DZ) did not meet criteria for ND and are theorized to be at low-genetic, low-environment (LG-LE) risk.
