In September 2003, Eileen Gu was born in San Francisco, California. Almost exactly two years later, Alysa Liu was born three and a half hours' drive south east in Clovis, California. Both girls had parents who emigrated to the United States from China and both would go on to become sporting superstars. Their paths to the top are similar – prodigious success, elite university education, Olympic medals – but differ in one crucial aspect: when Liu steps on to the top of a podium, The Star-Spangled Banner rings out; when Gu does the same, the Chinese anthem plays.