First let me say...STOP WORRYING!! All those values you have been promoting and modeling have not disappeared, just gone into hibernation for the next 5-7 years. I promise, they are all still there and when they get on the other side of adolescence, and they have had a chance to choose to make them part of who they are, you will be brimming with pride. Choose here is the operative word. Up until this point in their young life they have relied on you to orchestrate their life. You have been their #1, and they have counted on you to watch their back. Now they are literally biologically driven to watch their own back. Their new brain is showing them ALL the possibilities of life, not just the ones YOU choose to share with them. Part of raising a teen is trusting that you have already done a wonderful job, and now it's their time to experience the world as they see it. Think of it like a buffet table. In the past you chose their foods for them, knowing what you think they would like, and not wanting to waste any food. Now, they walk down the buffet line and maybe see the sushi and say: " hey, this looks cool, how come you never let me eat this."And off they go, trying new foods you never dreamed they would like.
So seeing all the possibilities of life is one part of what's driving this change in personality. The other part is the hyper sense of self-consciousness that is ever present especially in early adolescence. There is a constant worry that everyone is looking at them, and judging them. And if they don't wear the right clothes, have the same phone, listen to the same music, talk the same talk, then everyone, and I mean everyone will think they are completely and utterly uncool. This is where the clone-like behavior comes in. Its not about values, and I know it drives you crazy that they are making choices based on what other people think of them. But relax, it is only a moment in time. It is not a character flaw in your child, it is developmentally normal! This new brain of theirs is just realizing that other people think things about them, and feel that if they look/feel/ and think like their peers that all their flaws will be invisible. As they begin to develop a sense of their own identity (when they have traveled down the buffet enough times and tried it all before settling on some favorites), they will have renewed confidence.Come on, I know you drank the kool aid too when you were their age!
But beware, if you take the high road here, and continue to preach the sermon, your teen will feel judged/ criticized and never quite good enough for you. This doesn't mean that you don't have a say, it just means you have to take a circular route to get there, if you want to maintain the relationship you have taken the time to build. So when your tween comes to you with a request that you know is cause "all the other kids..." Here is what you can do. If it is unsafe, or truly inappropriate (like getting a smartphone..don't get me started on this one) you can use this "I get it moment": I get how important this is to you, and I know all your friends have it. And I know that not having it, will make you feel different from your friends, and I am really sorry about that, I know how that feels, but it just isn't safe and I am willing to take the heat from you to make sure you are safe.
So relax, all is not lost cause they want to look like every other kid on the block. You know they're special and unique and that is all that matters.