"Rape, however, is natural in the human. That's why every religion preaches against it and every code of law mentions it. If it was unnatural (and thus rare) it wouldn't get any attention at all."
Interesting. Let's take a look at your sentence with a substition of a single word:
Homosexuality, however, is natural in the human. That's why every religion preaches against it and every code of law mentions it. If it was unnatural (and thus rare) it wouldn't get any attention at all.
Natural is a much-overused word in these contexts.