Why do we teach our children to kill?

Why do we teach our children to kill?
The dictionary defines infant this way:

The word Infant derives from the Latin in-fans, meaning unable to speak. It is commonly used as a slightly more formal word for baby (the youngest category of child). A newborn infant is known as a neonate (neonatal) after the final stage of gestation.
en.wikipedia.org/wiki/Infant

And yet infant is the base root word for the word infantry

Is it me or is this way of it. Raise our children in a world gone mad by its parents. Then teach them to go and kill other children and their parents. When will our children stop being made accountable for the sins of their parents.

If we think about the vast majority of human problems.
Both on a personal level and on a world wide scale, it seems that they stem from from an inability to FEEL SINCERELY involved with others, and to put ourselves in their place.
Violence is inconceivable if everyone is genuinely concerned with the happiness of others.