Final answer:
If Cynthia has blue eyes, a recessive trait, it means that both of her parents must carry the blue eye allele, even if they have different eye colors.
Step-by-step explanation:
Inheritance of eye color is determined by multiple genes. If Cynthia has blue eyes, a recessive trait, both of her parents must have at least one copy of the blue eye allele. This means that Cynthia's parents can have different eye colors, but both must carry the blue allele. For example, one parent could have blue eyes and the other parent could have brown eyes, as long as both carry the blue allele.