Actually, yeah, they do lol. It’s part of the reason the average height of people has been increasing. Optimum nutrition helps people reach their optimum size, as dictated by their genetics. If they’re malnourished, their genetics may have them set at 6 feet tall at full potential, when in reality they’re only 5’8. This is only a real-world practical example though. There are far more extreme cases.
Look into feral children if you’d like examples.