Could you tell me if my twin went under general anesthesia and was fine, will i be fine too?

Yes: Risks from anesthesia are already very low, but a few of the most significant rare risks do have genetic factors. Risks like malignant hyperthermia and atypical cholinesterase run in families.

Probably: The genetic issues are likely not an issue. However, if your medical status is different, or if you are having a different type of procedure, your risk profile changes.

See below: All patient's are different. But having a close relative, especially a twin, undergo an uneventful anesthetic really decreases you chances of having an allergic reaction to the anesthetic. The risk of anesthesia overall are so small that I am sure you will be fine. Good luck.