"no single snowflake feels responsible for an avalanche".
The idea of "sexual deviancy" is almost a thing of the past. Fewer and fewer behaviors are considered aberrant. This is due, in part, to a common mix of pseudo-science and almost universally un-examined personal philosophy.
Let's start with the science. It's an easy road from evolution to pre-determinism (or from Calvinism to predestination, but that would be another debate). By this we mean that if we are a collection of cells that evolved through time to change into increasingly more complex states, then we by nature pick up habits and traits that help our species to survive. These traits are neither good nor evil, they just "are". A man seeks multiple sexual partners to increase his chances of offspring. A woman chooses a man based on subtle clues that let her know which one will produce the offspring most capable of surviving. Love is just the right mix of chemicals and the right time that short circuit the brain and allow us to feel the sensation that we write songs and poems about.
And by this measure you can also see that many parts of your behavior were pre-programmed from the start, they are part of who you are and cannot be changed. It is nature to want these things and imposing a morality that restricts these behaviors is then by definition, unnatural.
This leads us to the personal philosophy that so many American's carry around like a chip on their shoulder which I think was best expressed by a character on the show, Lost,
"Don't tell me what I can't do"
Now, in the beginning this was a war cry of a disabled man struggling to over come a handicap, but it became an excuse to follow his own course, where ever it lead, and who ever it hurt. We in America have a real hard time letting anyone tell us that our behavior is wrong, or gasp, bad. No matter the circumstance, we can, given enough time, justify our actions in the sound-proof chamber of our mind until we are convinced that the course we have taken is the only course we could take. And without any one to hold us accountable, or to question our actions, we will continue to make morally questionable choices that we would defend to the death if a stranger were to question them.
This goes well with our current (though new-found) religious introversion. At some point it became so repugnant to express any opinion on good/evil, God/man that to do so was the ultimate faux pas. That and politics. Should we digress and talk about how bringing religion down to the same level as politics has weakened the church and strengthened the state?
"Never argue with a fool, he'll drag you down to his level and then beat you with experience"
But this discussion isn't about me, a person on the outside, judging your actions. It's about how you or I determine whether our actions can or should be classified as "good" or "evil". We shall save that discussion for part 2.