Genes are a strong predictor of height (in certain populations), AND it has gone up tremendously in places like Japan. Both are true. To speak of the influence

Genes are a strong predictor of height (in certain populations), AND it has gone up tremendously in places like Japan. Both are true. To speak of the influence of genes also assumes a certain environment. If we look at western populations for example, the heritability of height in adulthood is something like 0.8. But this is predicated on that western environment where ~nobody has nutritional deficiencies. A uniform, high-quality environment means that there is little besides genes that can influence height. If something happened and a large portion of the population had such deficiencies, the influence of genes would be diminished.