I read in the guide that it is not necessary to purchase museum passes for teens although it is both cost effective and time saving for adults. If teen doesn't have a pass, is there a problem going to the front of the queue with the parents who do?
No idea of where you're talking about, but the short answer is, no.
Kids are de facto included on the pass-holder's ticket. Think of it as a family pass -- one hunk of cardboard for a slew of folks.
I think it depends on the country.
I usually don't get passes because they only pay if you see a lot of places (kind of like a train pass vs. point to point tickets) and my family revolts before we get to that point.
I always ask for a discount for the kids. The only place I didn't get a discount was Italy (and they were kind of snotty about it).
If, per chance, you are talking about Paris, then what you need to know is that children under 18 are admitted free to all museums and monuments covered by the Paris Museum Pass. If they stick with their parents, they can go to the front of the queue.
Thanks so much Everyone !