Hey Kim,
Thanks for reaching out!
This is a really interesting idea — our plugins unfortunately do not have any sort of support for this kind of feature at this time, however. 🙁 It’s indeed true that you can add an Additional Field to ask for a person’s age as they check out — but there is no way to either validate this input, or to show/hide the “Add to Cart” button based on its value.
Either thing is technically possible of course, it’s just not possible with our plugins “out of the box” at this time. Extensive custom coding would be required. If you’re keen on realizing these features on your site, then I would encourage you to check out this page of customization resources on our site → http://theeventscalendar.com/customizations There may be someone there who can build this set of features for you.
Sorry to disappoint, Kim! Please let me know if there’s anything else I can try to help with.
Sincerely,
George