According to the slop machine:

The average height for 19-year-old young adults is approximately 175.7 cm (5 ft 9 in) for men and 163.5 cm (5 ft 4 in) for women in China, compared to about 177 cm (5 ft 9.5 in) for men and 163–164 cm for women in the United States.

So yeah, it's exclusively racist prejudice based on historically colonialism-driven wealth differences.