Hey Megan
don't worry too much about that reply, its a perfectly reasonable question. However, what I would to see is some references to all this "research" that nale seems to like quoting?? I'd also be more than interested in which school taught him all this information, because it certainly wasn't part of my degree.
One comment on your original post tho, I'm not a fan of the jolly jumpers for a few reasons. When I was a student, we were always taught that they were bad news for a number of reasons, and as far as I know that hasn't changed in the last 10 years that I've been working in paediatrics. However, I don't recall predisposing a kid tospondylolisthesis being one of those reasons.
Sorry I couldn't be of more assistance.