Growing Uncertain
When a couple conceives a child, each parent contributes one of their own ABO genes to the baby. But, not all blood types are equal. The A and B genes are dominant, and the O gene is recessive. When an O gene is paired with an A gene, the A “wins out” and the child’s blood type will be A. If both dominant genes A and B are paired, the baby’s blood type will be AB. When Professor Lisa Johnson explained it again, the atmosphere in the classroom began to grow tense.