The Birds and The Bees - (proceed with caution: some material may be offensive to some)

I always wanted an open relationship with my children so that when they got to be teens they could come to me about anything.  ANYTHING!  And so far..... they have.  Do they talk to me about drugs? yes!  Do they talk to me about sex? Absolutely!!  masturbation? Yep, that too.   There really isn't a topic that is "off-limits", and I don't think that there should be.  I may not always answer a question if it is too personal, but they are always free to ask.  I answer them honestly and matter of factly.  Is this how parenting should be? By being open about these issues, does it diminish my authority as a parent?  I don't think so......My daughter often tells me that I am her Best Friend because she can tell me anything.  Can we be our children's "friends' and still be "the parent"? Or am I setting myself up for difficult times ahead?