I know this is going to be controversial, but many teens are not mature enough to know what is good and proper for them. Thus, in a natural state of rebellion, they will later claim to have been Confirmed under duress - either parental or from group pressure from their peers in school. This, in my opinion is not true duress, since these teens are too immature to validly object to being Confirmed. especially when they have been properly catechized.
Thee fact is, that so many teens today think they are mature-largely from exposure to sex and other adult matters in the mass media-when in reality they are still mentally and emotionally children.
If you don’t think this is true, just talk to any high school guidance counselor, or better yet, someone in the professional military that has guided youths through basic training. Our society is such that about 1 out of every 3 recruits is discharged before they complete basic training-largely due to immaturity on the part of the recruits. This is quite a bit more than what happened to WW II, Korean War, and Viet Nam era recruits.