Hey, cheers for the input! So here's an outline of how I see this working…
Roughly ten years ago, a company that manufactures cots did a production run of ~1000 and sent them out to distributors as normal, except this batch had a problem. Every person who bought one of the cots found it exhibited anomalous properties as described in my initial post, and it quickly came to the Foundation's attention. They bought in the affected families and found the children had a perfect 18 years of time-accurate memory, simply as if their whole lives had happened 18 years earlier than they actually would have.
Except all of them remembered 'my Uncle Jack, who took me on holiday when I was young.' None of the affected have a Jack in their family, and their parents denied any such holiday ever happened.
After the age when the children claimed the holiday took place, they all described increasing difficulties at school, anger issues, and struggling to integrate with other children. Interviewers described them as antisocial and withdrawn.
EDIT: I've been thinking about the connotations of what I wrote and I'd like to add that, whilst I'm still deciding on details, if this this skip goes ahead the anomaly will explicitly NOT involve sexual abuse of children. I have a couple of ideas for what the false 'holiday with uncle Jack' would involve, but it won't be that, or implied to be that.