The correct answer to this open question is the following.
Although there are no options attached we can say the following.
The sin that is mentioned in Genesis 6 is the sin of lust.
Neither of those. I think that it is time to interpret the Bible with an open mind and criteria. The Bible is full of metaphors. And this chapter of Genesis uses many of them.
More than a sin or rule, in these modern days we have to understand the invitation to be respectful when talking about man and women relationships. This is what I consider the message of this part of the Bible. Always respect the dignity of man and woman. Relationships between man and woman are no bad and are so natural to the degree of acceptance that this is the way that we are born on planet earth.
