How one sees “human nature” probably reveals a lot about one's self. The range of views is broad. Some may deny there is such a thing, seeing human beings at birth as blank slates. Some may see humans as intrinsically good and others as essentially evil and still others everything in between.
However, it must be that human beings are by nature social. Our species had to evolve this way to survive. But beyond being just “social,” human beings all want to love and be loved. Yes, perhaps there are those born with some failed wiring who we call psychopaths. In the normal case, we are born wanting to be immersed in warm relationships with others, quite apart from sex. This suggests that by nature, most of us are born being “good” people, eager to talk and listen, eager to learn and share, eager to exercise our minds and bodies while exploring our world. This is what it means to be homo sapiens.
Nurture takes us from this starting point and either allows us to grow strong and mature as self-confident, wise and kind beings or it tears us down. We either develop as secure and open egos with positive character traits – honesty, compassion, loyalty, inquisitiveness – or we become encased in what Freud called reaction formations, negative character traits formed as defensive mechanisms against the bad things that we suffer as we age. Few of us are saints or outright devils. Most of us come out somewhere in between and some shine even when surrounded with sorrow and want. By nature we are good. Departures from this owe mostly to the inequalities and inadequacies of our social organizations.
National character is analogous to individual character. The humans that make up any language, ethnic or social group start out and grow as we all do. But they are confronted by the “character traits” built up over history and many of these traits are collective reaction formations, expressing those events – real or as imagined – that have defined that history. Nations are departures from a common human inheritance and nature. But they are also real. And it seems that few of us are ready to live without them.