When my family moved back to the United States from East Africa in the mid-1980s, one might have thought it was a peak time of compassion for people suffering in faraway places. A glittering group of music superstars had recorded “We Are the World,” a smash hit charity single to raise money and awareness for the victims of a brutal famine that had gripped my mother’s home country, Ethiopia.But when I told my new grade school classmates of my origins, I was met with cruel taunts. I was awfully fat for an Ethiopian, one said with a snigger. Must be...