That's a good one to think about! but genes will be genes, like the genes to have dark colored hair. So meaning that, the genes to be tall will still happen. Nutrition and food is mainly to help survive and have cell production consist itself (which confusing since tallnes should be affected by that). It still is a genes though, as long as the body is provide with the least most needed nutrition, meaning that you have enough food that you wont die from starvation lol. You see, the body is a very complex system and when something like poor nutriton comes into play, it shuts down the least needed things such as the reproductive system. So i doubt lack of nutrition will affect height.
This is a guess though xP, its the best ive got xD
nutrition will play a major role in height. if someone has tall genes, they will still be tall in stature, but the will not be as tall as they are supposed to be, their body just doesn't have the adequate nutrients to sustain a tall stature.
If they were suffering from malnutrition, I doubt that their body would contribute the resources to grow very tall. Obviously they would still be genetically inclined to be tall, but persistent, chronic malnutrition can have a lot of negative affects on the body.