在此描述的這種紛繁多樣的性文本是人類性的本質，因為在動物中並沒有發現有這樣的現象。（在某些動物中有一些性的組合，但用來作比較幾乎沒有意義。）與高等哺乳動物大不相同的是，人類的性是變化多端的。確實，可以說每一個人的性都是獨特的。

The great variety and variability sketched here are typical of human sexuality, since there are not found in animals. (There is some variety in some animals, but it is insignificant by comparison.) In contrast even to the higher mammals, humans are a sexually varied lot. Indeed, each human being can be said to be sexually unique.