Facebook collects your data from Whatsup. They collect your information. You are not anonymous, since Facebook bought Whatsup and now owns that company. They collect data from that. The Germans are the only one that told Facebook to stop, if they do not have user consent, which they don’t, according to Expressen.
I don’t think you should publish anything in Facebook or Whatsup. Let their technologies be rejected and let this be an end of the Facebook era, as well as Whatsup era.
Parents should be aware of their children’s privacy. As a teacher I know many children use Whatsup. If you are a concerned parent, you should fight for your children’s rights.