The grapefruit's origins are uncertain. First described in 1750 as the "forbidden fruit" in Barbados, it took a while to catch on. Even when it was grown in Florida, it was mostly ignored.To learn more about grapefruit (well, practically everything), you can go here.
Better still, head to the nearest fruit stand or grocery produce aisle and indulge in the grapefruit. It will put sparkle in your morning, clear your sinuses, provide an elegrant broiled first course at dinner – and generally expand your citrus horizons. No longer "forbidden" but meant to be enjoyed.