Tay-Sachs disease in humans is controlled by a recessive allele (t). This disease is characterized by the inability to produce an enzyme needed to metabolize lipids in brain cells. Without this enzyme, lipids accumulate in the brain cells and gradually destroy the ability of the cell to function. Children affected with this disease usually die by age 5. What genotypes must be found in both parents in order to have a child with this disorder and what are the probability they will have a baby with this disease?