Why are Japanese tall and short?

That was decades ago, and now the average height in Japan has surpassed that in China. Isn't it incredible? Mainly due to diet, the southern part of China has a large population and mainly eats rice, so it is short in height. Japan's staple food is rice, which may also be affected by this. Nowadays, most Japanese eat bread and milk for breakfast, Chinese food at noon and Japanese food at night. Changes in diet have also changed the height of Japanese people.