- Blue eye is a recessive trait in human
- Receiving the recessive gene for a trait from each parent causes the offspring to have that recessive trait
- So, to have blue eyes requires receiving the recessive gene from each parent

Hence, to have blue eyes requires receiving the recessive gene from each parent
[Question]What causes a person to have blue eyes?
[Context]- Blue eye is a recessive trait in human 
- Receiving the recessive gene for a trait from each parent causes the offspring to have that recessive trait