Ancient potentates sometimes had the nasty habit of putting messengers to death if they didn't like the message. News of this would quickly spread among the messengers, so they would say only what pleased and flattered the ruler-only what the ruler was willing to hear. Like these old-time messengers, youngsters are vulnerable to the dictates of adults because grownups hold so much control over what happens and doesn't happen in a child's life. Children know this fact of life very well.
If we squelch a child's communications, we risk killing off the enthusiasm, openness, and honesty of the young messenger. But when we make it safe for youngsters to freely express themselves, we provide fertile ground for their growth and for a stronger, deeper relationship with us. Also, we can keep in better touch with what is happening in their world. Given less than half a chance, kids communicate openly and happily.
Achieving full disclosure isn't possible of even necessarily desirable. We all have private selves; neither adults nor youngsters are saints; and most saints never had kids. Let's face it, a child will never tell everything. (Did you?) But you want it to be safe for them to tell you anything that they need or want to.