eating foods high in protein at a young age having a brother or sister with blue eyes being overexposed to the Sun at a young age receiving a gene for blue eyes from each parent
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: What causes a person to have blue eyes?
Possibilities:
- eating foods high in protein at a young age
- having a brother or sister with blue eyes
- being overexposed to the Sun at a young age
- receiving a gene for blue eyes from each parent

receiving a gene for blue eyes from each parent