NEW YORK :With their competitive instincts honed by a fearsome sibling rivalry, the Macuga sisters, a trio of rising American stars, are vying to compete in three separate disciplines at the Milano Cortina Winter Olympics in February. The eldest, 24-year-old Sam, has embraced the high-adrenaline demands of ski jumping, Lauren, 23, competes in alpine skiing and 22-year-old Alli was named 2023 FIS Rookie of the Year in moguls. "We luck out that we are in different disciplines. We are so