What about people who don't seem to have any empathy -- for instance sociopaths? If empathy and altruism were inborn we'd all have them, yet we don't. And this optimistic view of human nature can't cope very well with the problem of evil either.
If evil is defined as looking after yourself and is innate too (because part of our evolutionary heritage) then how does it work with our innate altruism and empathy?
My view is that this is a completely inadequate way of thinking about morality. A few examples to show why -
If we all have empathy, why is it that people like to hurt other people? It is rare to find someone who has never said or done anything hurtful to another and got some satisfaction out of it; and some people find hurting others deeply pleasurable, and grow to like it more and more. How does that fit with a view of humans as empathic? We plainly do not have empathy for all, since otherwise there would be no people who are shunned or uncared for in our communities.
If we are essentially altruistic, then how do we account for meanness, envy, cheating and telling lies? How do we account for those situations in which people deliberately act in ways that will be unkind and unfair to others?
If evil is merely a name for self-interest, then why is it that people deliberately hurt and destroy, damage and deface, torture and kill - when it is of no benefit to them to do so, but just because they can?
My view is that we have great innate capacity for good and for evil, and that we are shaped by our choices towards good and evil. Goodness is hard - especially it is hard because the right thing, the empathic or altruistic thing if you like, is so often the thing we do not want to do.
I don't want to give away my money so that women will have a refuge from violence (one of the things I do); I want the women to have refuges, but I'd like to keep my money for myself and buy things for me and my family with it. Giving away the money is a deliberate choice to do something I don't want to do, a discipline. Doing the right thing so often isn't a matter of what advantages us, or of our feeling, but of acting by principle. It gets easier, a bit, if you practice, and there are benefits to doing the right thing. But they are not always immediate and may be intangible.
In the same way, doing bad things gets easier the more we do it, yet the satisfaction we get from doing what we want to do doesn't last. It's a case of diminishing returns.