My mom died at 50. My daughter was born 3 years later with the same first name as my mom, but a different middle initial. AARP spent -years- trying to get her to sign up.
AARP website cleary indicates that you have to be 50. So, I just now tried to join - with a fake name, fake address, and fake year of birth (2000). They flagged the address - so I put in a real address (not mine). Age didn't get flagged. took me to a billing page. Obviously I'm not going to give billing information (real or fake) so I don't know at what point in the process the age would get flagged, if ever.