Underaged children on social platforms give their rights up to their parents or guardians to decide. Yes, ultimately the physical choice is up to whoever has access to the account, but an underaged (I believe it's under 13, but I think there may be additional laws beyond that,) individual should not be allowed to make that choice themselves without parental permission.
It doesn't matter if not "everyone" does it. If it's allowed to be shown, that is that much more risk to safety.
Edit! I looked it up more... Apparently it's against the law to enable children to make any personal information publicly available. Even if parents have given permission. Not good... It would probably be the safest route to delete all personal ID in your profile if you're in the pup category :/