Task: Question Answering
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: Two sisters went to the hospital. The medics ran some blood tests and found out that Sue had sickle cell trait, while Mary had normal blood cells. Sue received treatment. 
Question: Which sister doesn't have a genetic abnormality?
Output (English): Mary.