Recessive. Arlene, Tom, Wilma, and Carla=nn George, Ann, Michael, Daniel, Alan, and Sam=Nn Sandra, Tina, and Christopher=NN or Nn
Work Step by Step
Since the marriage of Ann and Michael, both unaffected, could produce affected Carla, alkaptonuria must be recessive. Using this knowledge, and letting N=normal and n=alkaptonuria, Arlene, Tom, Wilma, and Carla must be nn since they are affected. George must be Nn since he is unaffected but some of his children have alkaptonuria, as is also true for Ann and Michael. Sam must be Nn since his mother only had n alleles to pass on to him. Not enough is known about Sandra, Tina, and Christopher to determine if they are NN or Nn, but they must have at least one N allele since they are unaffected.