Pedigree Characteristics X Both parents are carriers 25% of sibs are affected. Males and females are affected with equal probability 2/3 of unaffected sibs are carriers X The diseases are sporadic X The risk of offspring is higher in consanguineous marriage Both parents are carriers  The diseases are sporadic  The risk of offspring is higher in consanguineous marriage  25% of sibs are affected. Males and females are affected with equal probability Pedigree Characteristics  2/3 of unaffected sibs are carriers