That question only makes sense to people who belive free will exists. I can see it exist at a level, but not necessary when it comes to sinning. My experience, is that sinners often would choose otherwise if they truly had the choice, though the story how sin came into existence, as told in Genesis, is interesting.
I belive most sins as we know them, truly are harmful, but the term is also used to control people and their behavior. One example of this, is when modern people use it to keep an oppresive marriage between a man and woman intact. There is too much domestic violence around to make me belive in monogamy as the best solution, though I know people can thrive in it.
