人的身高分布服从近似正态分布是从很多统计数据看出来的.所以就要问，为什么会这样呢？

引用：

It [clt] explains why many human characteristics follow the normal curve, as attributes such as height or weight can be thought of as a sort of “average”. If we think of human weight or height as being a “sort of mean” of many factors (such as heredity, diet, race, sex, many others) then the Central Limit Theorem would lead us to expect that such human characteristics will follow the normal distribution.

这就是说正态分布显示影响身高的独立而差不多重要的因素很多，没有主因可集中研究用以帮助预测一个个体的未来身高。在此意义上说预测难，或预测的研究难，因为无主因可抓。假若是[a,b]上的均匀分布，则研究一个人的身高就很有可能发现影响所有人身高的共同原因。