Seeing as how you asked this question yesterday on the ask cruisemates staff section and were given the answer, it appears that you do not want to belive the answers you got, you can find the answer directly from Carnival's web site. Go to www.carnival.com, click on guests services, then click on ticket contract, then scroll down to section 6 (d), there you will find the official policy on drinking age and responsibilty. Then go back to their main page scroll to the bottom of the page and click on FAQ, type in gambling, then click on are there any age restriction for on board activites, there you will find the gambling age.
Jedgar, being new to the message boards I didn't realize I posted this twice on the same web site. I must say your response was very rude. It will note encourage me to ever ask questions of the staff again.