Tall Girl

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 usually due to gigantism or dwarfism; which are medical conditions due to specific genes or to endocrine abnormalities.
In regions of extreme poverty or prolonged warfare, environmental factors like malnutrition during childhood or adolescence may account for marked reductions in adult stature even without the presence of any of these medical conditions. This is one reason that immigrant populations from regions of extreme poverty to regions of plenty may show an increase in stature, despite sharing the same gene pool.
The average height for each sex within a population is significantly different, with men being (on average) taller than women. Women ordinarily reach their greatest height at a younger age than men, because puberty generally occurs earlier in women than in men. Vertical growth stops when the long bones stop lengthening, which occurs with the closure of epiphyseal plates. These plates are bone growth centers that disappear ("close") under the hormonal surges brought about by the completion of puberty. Adult height for one sex in a particular ethnic group follows more or less a normal distribution.