When our DD16 was in sixth grade, she was supposed to read books older than high school - according to her aptitude. I went to her teacher and asked if she could read "popular" books more around her grade level. At this point, we had proved that she could read almost anything. She read books that the other children were reading and it made her happy and gave her something in common with others her age.

It has not "ruined" her reading or anything. It was just a small way for her to fit in.