A Rapist In The Family - Further Reflections

Not so long ago I wrote a blog titled "A Rapist In The Family". It raised the rather uncomfortable fact that at some point in our family history, a male probably forcibly copulated with a female, impregnating her and ensuring his genetic code found its way into the next generation. Now if you ask the average non psychopath you can be reasonably confident that agreement can be reached that rape is a bad thing. Yet as a skeptic what grounds have I to say this? My ancestor, smaller brained and more brutish was doing no more than avoiding the Darwin award by reproducing, and he was following a natural compulsion.
So what changed? How can I transition and argue that rape is in fact bad?
Well I happen to think the answer is rather straightforward. And I think the key to it probably lurks in the evolution of language. When our species stumbled across this facet it was an absolute game changer; it meant that whole new avenues of communication were made available to us. One could argue that language is the thing that undergirds all sociobiological transactions in the modern world. 
Yet we still have rapists? And people of violence? 
I probably don't need to spell out the rest. What I do say is that it does put a pin in the balloon of any claim of objective morality, this rather tenuous idea that in order for us to know right from wrong we must appeal to some transcendent force, or as people commonly refer to as God. You see, it doesn't seem to move us any further forward? We have reasonable explanations for why we can say of a certain act that it is wrong or harmful, and to the modern world most of us have a clear understanding that rape is detrimental to the flourishing and wellbeing of its victims. We can say this despite knowing that we didn't always think this way, and we can acknowledge that we are the products of a long line of human ancestry. Now I chose rape as just a single emotive example to make a greater point; namely that our moral leanings are accumulated over time and are informed by many factors. Can a person still rape? Well yes? They can expect to find themselves subject to the laws we have established to protect ourselves, however. And how did these laws come about? Once again we can doff our cap at language as the conduit that made this possible.