Normal red blood cell shapes is a dominant trait. Sicklocell anemia is a recessive trait. USING THE LETTERS "A" for the dominant normal blood cell shape or "a for the sickle cell allele, answer the following (2pts) Attached earlobes is a recessive trait. Susan and all of her immediate family have attached earlobes but her naternal orandmother has unattached earlobes. Use the letters (R or r ) to.