E.R.
HUGS to you M.,
First I want to let you know that adopting has nothing to do with what you are going through. I did not adopt and am going through the same thing with my children. Some of the attitude is lessening in my older child as she grows and learns. She listens more now then she ever did. The other one.. nope won't listen to anything.
I have to agree with the child that said they are the ones making these choices. They choose to follow your good example or not. It is very painful to let them follow their own choices.
Two things come to mind. One is that as they are responsible for their own choices, you are responsible for how you respond to their choices. In other words, stand your ground. Eventually they will respect you for your choice. The second is that, the only thing you can change at this time is how you feel about their attitudes. You need to remember that it is not really personal. If SuzyQ down the street was their mom and took the same stand, they would have the same reaction. Stand firm, send them love and eventually they will come around.