my 4 year old has developed a strange habit of eating what other children bring for lunch at school. how can i stop this? it is embarassing. i have spoken about it but can't see any change.

my child had started doing the same a few months back. i told her that when you share foods from each other's tiffin, it can sometimes bring in the germs even if you can't see them. i told her that sharing food like this from the tiffin can make you get cough or cold, and fever also, and then you need injection from the doctor. she stopped.