Task: Question Generation
Input (English): Background Paragraph: Some individuals have a specific mutation in the primary sequence of their hemoglobin molecules that causes them to aggregate, resulting in a deformation of their red blood cells. This abnormality is genetic in nature. A person may inherit the gene from one parent and have sickle cell trait (only some of the hemoglobin is hemoglobin S), which is usually not life-threatening. Inheriting the gene from both parents will result in sickle cell disease, which is a very serious condition. 
Story: Dan studied two groups of individuals. Group S that had sickle cell anemia, and group B which had normal hemoglobin. He was fascinated by the results.
Output (English): Which group didn't have aggregating hemoglobin?