Passage: Studies show that there is a correlation between small stature and a longer life expectancy. Individuals of small stature are also more likely to have lower blood pressure and are less likely to acquire cancer. The University of Hawaii has found that the “longevity gene” FOXO3 that reduces the effects of aging is more commonly found in individuals of a small body size. Short stature decreases the risk of venous insufficiency.When populations share genetic background and environmental factors, average height is frequently characteristic within the group. Exceptional height variation (around 20% deviation from average) within such a population is sometimes due to gigantism or dwarfism, which are medical conditions caused by specific genes or endocrine abnormalities.The development of human height can serve as an indicator of two key welfare components, namely nutritional quality and health. In regions of poverty or warfare, environmental factors like chronic malnutrition during childhood or adolescence may result in delayed growth and/or marked reductions in adult stature even without the presence of any of these medical conditions. Some research indicates that a greater height correlates with greater success in dating and earning in men, although other research indicates that this does not apply to non-white men.Height is a sexually dimorphic trait in humans. A study of 20th century British natality trends indicated that while tall men tended to reproduce more than short men, women of below average height had more children than taller women.

Question: What causes height variation?
gigantism or dwarfism