I am intending to give users a chance to verify their accounts on my website by integrating with facebook login. This is due to issues I have with users causing mischief with multiple accounts.

However, I need to know that it's not just a new facebook account they just created for this purpose. I don't think there's a way to get the date the user joined facebook from the API? However, there may be a way to check the date of the first post. Or it may be faster to check if a post exists say more than 6 months ago?

Any ideas on this?