[sigmaxipi]

There is an interesting rule in COPPA that is the cause of this bad experience: http://www.ftc.gov/privacy/coppafaqs.shtm#teen

For sites that choose to age-screen, age information should be asked in a way that does not invite falsification. See Question 39, below. In addition, we recommend that sites that choose to age-screen employ temporary or permanent cookies to prevent children from back-buttoning to change their age in order to circumvent the parental consent requirement or obtain access to the site

...

However, as described in Question 38, above, should you choose to block children under 13, it is important that you design your age collection input screens in a manner that does not encourage children to provide a false age in order to gain access to your site. If you take reasonable measures to screen for age, then you are not responsible if a child misstates his or her age. For example:

...

Not encouraging children to falsify their age information, for example, by stating that visitors under 13 cannot participate on your website or should ask their parents before participating. In addition, a site that does not ask for neutral date of birth information but rather simply includes a check box stating “I am over 12 years old” would not be considered a neutral age-screening mechanism.

[pjscott]

Does COPPA think that children were born yesterday? Who would keep falling for the old "what year were you born?" age-verification trick?

[modeless]

This is the important bit that people miss. Google isn't allowed to warn you that changing your age will apply restrictions to your account, and they aren't allowed to let you easily undo it after it's done. This is what happens when Congress dictates user interfaces.

[cynwoody]

So, in effect, this means a kid is 13 as soon as he figures out he needs to be 13. OK.

Not all kids are created equal, and some kids will be 13 sooner than others. Some might argue that's not fair. But, back in the day, I would not have been among them.