Unattached earlobes (EE or Ee)are dominant over attached earlobes (ee).A couple both have unattached earlobes.Both notice that one of their parents on both sides have attached earlobes (ee).Therefore,they correctly assume that they are carriers for attached earlobes (Ee).If the couple proceeds to have four children,then
A)they can be certain that three will be heterozygous and one homozygous recessive.
B)if the first three are heterozygous,the fourth must be homozygous recessive.
C)the children must repeat the grandparents' genotype (Ee).
D)all children must have unattached earlobes since both parents possess the dominant gene for it.
E)two heterozygous,one homozygous dominant,and one homozygous recessive is a likely outcome,but all genotype ratios are possible.

Question

Quizplus · Accepted Answer

Since both parents are carriers for attached earlobes, they are each Ee. When they have children, each child has a 50% chance of inheriting an E allele and a 50% chance of inheriting an e allele. Therefore, the genotypes of their children can be any combination of EE, Ee, or ee. However, based on the laws of probability, the most likely outcome is two heterozygous (Ee), one homozygous dominant (EE), and one homozygous recessive (ee) child.

Unattached Earlobes (EE or Ee)are Dominant Over Attached Earlobes (Ee)