Is possible to get an AAA at the age of 16 if my family has a history of aaa?

Rare, not impossibl. Yes it is possible. Abdominal aortic aneurysms (and thoracic ) were reported in children as early as 6yrs. Unlike adults which atherosclerosis etiology. In children they are very rare and etiology due to vasculitis( inflamtion of vessels ) as in takayasu's arteritis, marfan's due to weak collagen, tuberous sclerosis.Need surgery as soon as diagnosed.
Very unlikely. It would be extremely unlikely to develop an AAA at the age of 16, even with a family history. Aaas occur most often in men >65 yrs who have ever smoked or women >65 who have ever smoked and also have a family history. It is possible to develop an aortic dissection at a young age if you have marfan's syndrome. This affects the thoracic aorta.