My grandpa had a aaa because he smoked what are the odds i have one i'm 24 and have heartbeats in abdomen and back ?

AAA in grand father: No only smoking but high blood pressure and high cholesterol and family history. Check your family tree for any others with AAA. Everyone has heartbeats in abd and back. Unless you are dead.

Too soon to be: concerned. Even with a family history, age 24 is too soon to be worried about AAA. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex.

Unlikely: AAA (abdominal aortic aneurism) would be extremely unusual given your age. It generally takes years to develop in those who are prone to them and have certain risk factors like smoking, high blood pressure, and high cholesterol. It is possible you may be genetically more likely to get one later in life, as your grandfather had one so you should keep your controllable risk factors in check.