David Hume, himself a freethinker, formalized the fact vs value distinction which boils down to saying in more modern guise that science can inform but not determine ethics. An is remains insufficient on its own to justify an ought.

Without some outside intersubjective value system as a check, we might wind up with eugenics or travesties such as the STI experiments of Tuskegee and Guatemala.

And the hard-wiring of morality, if so, is insufficient to justify morality. This sort of morality limits itself to ingroups.

It is a common to the point of banality, for Christian apologists to state that. "You can not derive morality from science and reason." But of course you can quite easily, as my quote below makes plain. What the apologists are actually saying of course is, that you can not derive Christian ethics and morals, from science and reason, which is quite possibly true. But in doing that they are of course confusing the subjective elements of their own peculiar ethics, with ethics, some of which can be objectively derived, as a whole. Or perhaps just as Christians often do, assuming that Christianity is a synonym for good, and all that is not Christian is bad.

And it is highly unlikely that you could derive Christian ethics from science and reason, because why indeed would any sane and or reasonable person, want such a set of truly horrible ethics. With their anti-environmental, end of times, next world, position, their promotion of guilt, misogyny, anti-trade, anti-investment and their empirical racism etc. etc.

In short, it is wrong to confuse Christian with moral or ethical.

My quote which I think that you have had before.

"Do I want to be happy, safe, content and enjoy human dignity ? A. Yes. Am I more likely to be those things, if I live in a world where happy, safe, dignified and content, is the general rule for most people ? A. Yes. Then is it worth my while to make some investment in everyone else ? Of course."

Plus the thought that even if we are happy and prosperous now, Anyone may one day be at the bottom of the social pile. And therefore it is better for all, as insurance, if the bottom of the pile is not too bad a place to be.

A third reason, is simple animal instinct. We are social animals, and therefore things, including others, matter to us. Indeed all the moral systems in the world would not exist unless they were driven by some animal instinct and emotion, since reason alone with nothing to drive it, or aim for, produces nothing. Nobody started cooking because scientific evidence, or religious belief, made them think it made food healthier, or even showed them why they should value health at all. Nor would anybody have invented morality without some motivation, and if that does not come from god or some supernatural origin, then it must be hard wired into us, even though the outputs of that hard wiring may vary greatly between cultures." There are probably hundreds more ways to develop morals and ethics by science and reason alone, but those three will do for now.