M.P.
I had been reading about why kids lie. Anywhere from the internet to seeing it on the news. Since toddler age when they finally realize that they need to hide something that they did to not get in trouble, yeah it becomes habit. I am trying to teach my 7 year old that it is best to just talk about it, not ask why did you do it or why are you lying. If you know what they did and they are lying about it, just stating that you know and talk about the reason and reassuring them that talking about it is better than hiding it. If they lie then they get in more trouble. Just talk to you're teen and let him or her know that you are with them and not against them and communication is always the best policy. Hope this helps and let me know how it goes.
Bye =)