I have a 19 year old and a 21 year old that will be going on our next cruise. I've heard of the 1820 society, I'm wondering if they are strict about ages? My 19 yr old might possibly be interested in joining, but almost definitely only if his 21 yr old sister is able to join as well. To be honest I suspect my 21 yr old may actually have more interest in it than the 19 year old, but that's beside the point. Anyone able to comment?