Before Caroline Marks ever won her first surfing contest and long before ever earning a spot at the Tokyo Games as her sport makes its Olympic debut, there was simply this: Trying to impress her big brothers. That’s what lured her to the waves. Growing up, the backyard at the Marks house in Melbourne Beach, Florida, was like a carnival of fun—trampoline, self-built motocross track, basketball court, and room for skateboarding. But right across the street was an even bigger attraction—the ocean, where the crashing surf always beckoned her brothers. There she was, more of a horseback rider then, trying to join in on the wave-riding fun. She quickly rose from tag-along to “ Grom ”—that young kid who surfs better than you—to World Surf League standout to her current role of contender when surfing hands out its first Olympic medal. “My brothers play a huge influence in how good I am today,” said the 19-year-old …