I think one thing I've noticed is sometimes overlooked in these discussions of human nature is that is an important sense in which human nature is not exactly what we're born with. The human brain is born "scarce half made up". It takes another 21 to 22 years from birth to completely form. And various human characteristics are not "wired for" until the brain has reached certain stages in its development.
Consequently, it can be misleading to look at an infant and see its behavior as indicative of human nature. For instance, I've heard several times over the years from various people that humans are naturally selfish -- as demonstrated by the fact a new born is selfish. The argument is made that our true nature is best shown at or near birth -- before nurture takes over and "corrects" nature. But that's a poor argument because certain human characteristics will, all else being equal, develop in the course of time. An example would be our capacity for compassion. It seems to develop around the age of seven in most of us. So, at earlier ages, we might appear to be organisms who naturally lack compassion and who must learn it. But in fact, any normally developing human will naturally learn it when his or her brain begins to get wired for it at around the age of seven.
Just a thought.