Whether you believe in Adam and Eve or Mitochondrial Eve you believe that everyone on the planet is ultimately descended from a single pair of humans.
There are a few Bible believers that think God has taken a hand in human development since then (curse of Ham and the black race - a rather racist and vile view, probably others I've not heard of). But almost every religious and all Darwinists believe in variation within kind, and despite quite a bit of variation all living humans are of the same species.
There is certainly a mix of natural and non-natural evolution within the process of human evolution. For example, being selected for soldier duty based on observable characteristics. Being selected for death because you were Jewish and living in Nazi Germany are just 2 clear examples of artificial selection pressure.
Being considered a more desirable mate because you are tall, short, etc. clear falls in the natural selection category.
It is clear a mix of selection styles in the human population.
We also have environmental factors that affect height. Nutrition and health care are simply the most obvious factors. Given the short timescales for the amount of change and the fact that we also see similar changes in other countries as they have modernized we can be quite comfortable in assigning most of the modern change to environmental factor.
We also have plenty of examples of isolation populations of humans being considerably taller or shorter than average. So clearly genetics may also make a considerable difference. As populations interbreed, genetic differences become a more minor component in human variation.
Though the details may be of interest, the broad strokes of this question were already well-known and accepted by almost every person with a modern education.