Hey! It looks like you and your son are sharing iCloud accounts. To fix this, read the following that was taken from this post:
You are sharing the same iCloud account. When you do this any data you sync with the shared iCloud account, such as contacts, is merged and will appear on all devices connected to the account. To fix this you both need to have separate iCloud accounts.
To fix this, first decide which iPhone will be keeping the current iCloud account. On the one that will be changing accounts, if you have any photos in photo album that you want to keep on this phone, save these to your camera roll by opening the photo stream album in the thumbnail view, tapping Edit, then tap all the photos you want to save, tap Share and tap Save to Camera Roll.
Once this is done, go to Settings > iCloud, scroll to the bottom and tap Delete Account on your son's phone. (This will only delete the account from this phone, not from iCloud. The phone that will be keeping the account will not be affected by this.) When prompted about what to do with the iCloud data, be sure to select Keep On My iPhone. Next, set up a new iCloud account using a different Apple ID (if you don't have one, tap Get a Free Apple ID at the bottom). Then, turn iCloud data syncing for contacts, etc. back to On, and when prompted about merging with iCloud, choose Merge. This will upload the data to the new account.
Hopefully this solves your issue,
Bryce 🤠