Children are not born "tabula rasa". From the day of birth, some babies cry harder, some louder. Physical differences alone immediately begin to shape the human mind so by the time children are able to run and play, a lot has been decided for them.
The parenting phrase that builds a victim and teaches a child to be bullied is...."Don't be a tattle tale."

What exactly does someone mean when they say this? I have several ideas of the intent: 1) don't make up stories (if there is some indication that the child may be fibbing just to get the other child in trouble), 2) stand up for yourself, 3) don't make a big deal out of little problems, or 4) I'm too tired/busy to deal with either of you right now
However, all of these messages translate to victimization for the child "tattling". If the child isn't lying, they learn that adults are not worthy of trust. If they are lying, that should be addressed by the parent in a more direct manner anyway. If the child could stand up for his/her-self, they wouldn't have come to an authority figure for help. What seems like a small problem to you could be a big problem for a child and if they child doesn't feel they can turn to an adult for help, the "small" problem can escalate into a big problem that the child cannot turn to adult for help on. And the last message simply tells the child they are not important enough to deserve help.
The "other" child also gets a message when they hurt, offend, or push the limits in some way with another child and that child's "tattling" is dismissed. It tells the "other" child that what they did was okay. It tells him/her that they are in charge of other (vulnerable) children. It gives them permission to do it again.
This phrase, uttered so flippantly needs to be reviewed. "Tattling" is seeking the guidance of an adult and being told not to seek that guidance creates a foundation for mistrust between child and adult and sets a foundation of disrespect for authority in the "other" child. Neither foundation has a place in our society.
So, kids, start tattling and parents - start paying attention.