If you look at the traits that people utilize to get along well with others, virtues such as empathy, consideration, respect, and tolerance, would be some of the notable attributes that those that do this well often have. On the other hand, traits such as selfishness, obstinacy, immaturity, and jealousy are basically not the attributes that are the characteristics of those that want and do get along with others.
When you take a look at children growing up and their dealing with others, the basic characteristics that parents really don't need to teach their children is how to be more selfish, more aggressive, more sullen, and more disruptive, because many children already have enough of each of these characteristics in the first place. Instead, parents want their children to get along well with others, so that they will share, they will be fair, and they will be more inclusive, all things that make for not only better children, but also a better world.
The fact that it is almost universal that parents when addressing their children's behavior, wish for better behavior from their children, would seem to indicate strongly that the very things that we wish for from our children, should be the very things that adults should be about in their own lives, for it isn't good enough to preach tolerance to youngsters if we are not tolerant ourselves, it isn't good enough to encourage children to control their temper, if we can't do the same, and it isn't good enough to impress upon children the value of thoughtfulness, if we are impulsive in our actions.
The very lessons that children need to learn must be the lessons that we ourselves have learned well, or else we are poor exemplars of what we should be as the parental authority to our children. It is somewhat amazing how parents can clearly see what children are doing wrong with other children, such as being unnecessarily mean and selfish, and wish to see that corrected, but somehow aren't able to see themselves in the exact same light when they do the very same things in their own lives.
As good as childcare can be, as good as teachers can be, as good as a given household can be, children need to be taught the best appropriate behaviors, and further, in order to demonstrate that they have actually understood the lesson, they must be given the opportunity to make the right decisions with their peers in real life, and when they are successful in such, receive acknowledgment of such, and when unsuccessful in such, the lesson must be redone and redone, until it is done right.
Of course, some children are going to fail at some tasks, but parents and other parental authorities are far better off trying to improve such behavior now, before it becomes absolutely ingrained, than ignoring such, and just hoping that it will disappear over time, which, it might. The bottom line, though, is that behaviors developed in childhood, good or bad, often develop into good or bad habits in adulthood, in which these habits once rooted are hard to dislodge, which is why parents and parental authorities must do their best to train up a child in a manner that will consist of the characteristics of a good person, today, while striving also in their own lives to be that better person, themselves.