Exactly how does fakebook decide an account is fake?

[Joey]

In our household, we have but one humble device, Kindle Fire 1st Generation. We have a large family & each of us uses the Kindle to log into facebook. When my brother visited, he didn't yet have an acct so he started his on our Kindle. The very next morning, he tried to log into facebook and they wanted to verify his identification.

I know it is their site & they can choose who stays or doesn't. Guess I'm just kinda whining because if facebook is simply going by the IP address when checking the validity of an account, that's bogus for those of us whose entire household and guests use the same device.

So, is there a way that we could contact facebook directly to talk to them about this?
Also, is there something in our actions that raises a red flag with facebook to make them suspect the acct is fake?
Trust me, I commend them for protecting the public. I'd just like to be able to figure out this issue to avoid getting us all deleted, having to start over again.

Thank you in advance for your help. Our family plays Bingo Blitz together through facebook. Its fun & brings us all into the same room. Much like a board game back in the day lol