appropriate adoption language

Since entering the world of adoption, I have noticed that books and articles on the use of correct adoption language are quite prolific. Why is this? I would assume, and have even experienced, that others lack proper etiquette when referring to adoptive parents, adopted children, and birth parents.
People make comments to adopted children, asking them about their “real parents,” when what they really mean is either biological, or birth parents. Parents of both biological children and adoptive children drop their jaw in astonishment when asked if the adopted children are “their real children.” When some refer to a child that was placed for adoption they often say the child was “given up for adoption.”
It may seem like there’s nothing wrong with these statements, but to adoptive parents there is plenty.
Recently I heard a sixteen year old girl talking about her birth mother. When speaking of her mother’s choice to put her up for adoption, she said, “I don’t understand why my birth mom gave me away.” Then the adoptive mom repeated the words. I was shocked. I felt horrible for teen who had grown up hearing that her birth mother had “given her away,” as if she were something that needed to be thrown out, which of course is not the case.
This exchange reminded me of a post I meant to write a few weeks ago. It was supposed to be about my own lack of decorum when referring to adopted children. My husband and I were in the car one day, and we were talking about a family who had both biological and adopted children. I said something about the families “real children.” WHAT?! Immediately my hand went to my mouth as if to stop what had just come out. Too late. As an adoptive parent I should know that is not acceptable to say. Not too surprisingly, I have a lot to learn!