People are conscious of sex just as they are conscious of hunger. If hunger is a natural, physical demand, then sex is also a natural requirement of the body. For a person to feel hungry is natural and it is not a sin. But if he steals food, then it is sinful. It is something unnatural. Likewise, the consciousness of sex is natural and is not reckoned as sin. Only if one uses an improper way to satisfy his desire does he fall into sin.
Sex consciousness is God-given. Marriage was ordained and created by God. It was instituted before, not after, the fall of man. It happened before Genesis 3. As a matter of fact, God introduced it in Genesis 2. Hence, sex consciousness existed before, not after, sin entered into the world. It is important to know that there is no sin in being sex conscious. Sin is not primarily involved, for the very presence of this consciousness was created by God.