It depends on how you define cheating. Do you mean cheating marriage partners? I think everyone has felt attraction towards others even when they are in a loving relationship. There is a difference in the way one handles it. Someone might accept it as a passing fancy, others might act on it. Is thinking about someone else cheating?
Every human being is capable of all the things such as lying. cheating, stealing....A free being is not bound by conventional morality, only his own ethics and the knowledge that for every action there is a consequence. One is free only when one can take full responsibility for his own creations.