One of the harder things to do when writing science fiction, or any genre that is not set in the present is to step outside your own biases, to create characters who are very different from you.
This sounds both obvious and simple but it is neither.
For example, I am an American, I like to think the best of my country, its people and our government. I can’t however allow that to mean that I make American’s in my story angels. Nor can I allow the opposite, for a people I dislike to be nothing but demons, caricatures without depth.
You have to allow groups who you like to sometimes be evil, and to have dishonorable members. Just as you have to allow the opposite. There were good and honorable men even in the Nazi party after all.
In one of my first drafts, it was only the US who had any real presence when the first colonies started to launch off planet. I realized that that made no sense. I might like the idea of the US getting into space and acting with honor but given the huge economic motivations, that would hardly have been realistic.
Even those things that you may think are inherently part of the human condition may not be. Make sure to know the difference between culture and biology.
Loving your children
The sad fact is that if you go back far enough in most societies people routinely abused their children, including leaving them to die by exposure if they were unwanted (ancient Greeks for one example). The idea that parents do or should love their children unconditionally is part of our culture, not part of human biology.
America had laws to protect animals from abuse before we had laws to protect children. A major case against child abuse was won by an animal rights lawyer arguing that children are mammals and at least deserve the same rights that animals have (Mary Ellen Wilson in 1870’s).
Marriage originally was a simple trade. The women agrees to provide her limited ability to have children, the man agrees to use his superior strength and endurance to provide for her. While obviously wives did more then just give birth, that is the only thing they did that only they could do. Everything else they did a man could do. Some of the things he could even do better (hard physical labor).
Love was not a factor. Love became embedding in the culture of the west during the middle ages somewhere around the end of the 11th century. If you look at literature before the 11th century romance as we would define it today is rare to nonexistent.
Even in other modern countries love is not seen the same way it is here. After all, you can hardly have both massive numbers of arranged marriages and a belief that love is what matters most in a relationship.
Tribalism is the feeling of belonging to a larger group, and of the feeling of not belonging to others.
While it might be easy for me to think of everyone being part of a nation that is not the case. It is not unusual for a people to think of themselves first, their family second their village a distant third, and their nation not at all.
In fact, seeing anyone beyond your family and tribe as being “one of you” is a relatively new development in human history.
Making your own way in life
It is a very common theme in both our media and our culture that you should go your own way. Walk the less traveled path. While that is an important part of our culture there are cultures where the opposite is true. There are cultures who are more collectivist then ours, such as most Asian cultures.