Earlier quoted context omitted.
Sadly, I think you're going to have to ban them. COPPA[1] makes it risky to have children under 13 on your web site without clear parental consent. ..you could let them send in a note from their parents to get unbanned :-) 1. http://en.wikipedia.org/wiki/Childrens_Online_Privacy_Protec...
There can be a very real issue if HN accounts have an age or birthdate associated with them which indicate that the user is under 13. In that situation where knowledge of age is in the hands of the website operator, the FTC has taken notice, and action. See Path's recent FTC COPPA ruling as an example. So, if HN internally keeps a reference from votes in the under-10 category of this poll to the accounts they came fr…
Path's case is different, since the form asking for the birthdate was made by them, so they knew they had that information.