> What's the next study? People with brown eyes do more drugs? Actually, that needs to be studied! Mutations in the melanocortin-1 receptor (the "red head" gen

> What's the next study? People with brown eyes do more drugs? Actually, that needs to be studied! Mutations in the melanocortin-1 receptor (the "red head" gene) affect eye color and also affect sensitivity to opioids (painkillers).