for a girl i'd say yoga, pull ups, and bicep curls(low weight high reps). I know a couple of girls in dance who've had the same problem.
If you amputate your arms you can get rid of it forever. Furthermore because of your lack of arms it will be harder to eat, so you'll lose fat elsewhere as well.
it is genetics,but weight lifting really helps.
push ups... or pick up light wieghts and doing as much as possible
I suppose there are weight lifting exercises that you can do that will target toning your arms. You can buy light weights. Google it- I'm sure there are plenty of videos or sites that will instruct you.
Wear long sleeves