When we say that we feel something is wrong or it seems unnatural what we really mean is that it is different to what we used to.
When I was young it felt wrong to me for women to be bosses at work. But, with hindsight, I now know that the idea of a woman being a man's boss was just an idea that wasn't yet normal. I don't feel that murdering someone is wrong, I know it is wrong and I know why it is wrong. Neuroscientists have even identified the part of the brain that is malfunctioning in people who don't know that murdering someone is wrong. This is the part of the brain that allows us to empathise with other people.
Therefore our morality should be constructed with constant reference to empathy and not received law and all existing law should be tested against empathy.