There are a multitude of synonyms for the term "sexual natures", many of which have slightly different connotations. Some possible synonyms might include "erotic tendencies", "libido", "intimate proclivities", "carnal desires", "amorous impulses", or "erogenous preferences". These words all suggest a similar idea of a person's inherent sexual disposition or desires. However, depending on the context in which they are used, some words may be more appropriate than others. For example, the word "erotic" might be used to describe a person's sensual or passionate nature, while "libido" might describe a more general level of sexual arousal or drive. Ultimately, each of these synonyms provides a slightly different nuance to the idea of "sexual natures," but all convey a sense of instinctual attraction and desire.