ZHANGJIAKOU, China—Ashley Caldwell thinks of Christopher Lillis as family, and Justin Schoenefeld as something even more. Together, they’re Olympic gold medalists. The trio of Americans won gold in the Olympics’ first mixed team aerials event Thursday, giving the United States its first medals in the freestyle skiing discipline since Jeret “Speedy” Peterson in 2010. Caldwell was a precocious, breakout star when she made her Olympic debut as a 16-year-old at the 2010 Vancouver Games. The 2017 world champion is now in her fourth Olympics but had never finished higher than 10th. The 28-year-old Caldwell and Schoenefeld have been dating for about three years, making her breakthrough to an Olympic podium all the sweeter. “I’ve been in the hunt for a gold medal my entire career,” Caldwell said. “To do it with these guys is incredible. Chris has been like a brother to me forever, and Justin is the love of …