It's very possible. It depends on what the original diagnosis is as not every diagnosis is related to genetics. In saying that though is you and your twin brother both have the exact diagnosis then its highly likely to be a genetic factor. You may be able to do the genetic testing, this may answer your question.

I've had epilepsy since I was 8. I have a twin and she's never had it, and I hope she never does!
Having a seizure or epilepsy has to do with your brain. Now... I don't know if sharing a womb, or splitting an egg with someone else will play a part in that? We can come up with tons of theories... but try not to stress about it.
Take it to your doctor. Maybe they could help you figure out this dilemma.
Good luck.

Hang in there and try and stay pos

JessicaC2 yes I did share a womb with my brother but surely that would not be a reason why and to go even more detail about it when I was 4-5 years old I had a convulsions fit but then two weeks later my twin brother had the same thing happen to him and I’ve had the genetic test done on me and my twin and it came out all okay so I’m not sure why it happened to my twin when he was younger then he out grow it then it happened to me but I got mine because my ex’s girlfriend got me beat up to the point I had epilepsy

I get from where you are coming from, I have had a similar situation, when I was younger and as growing up as a kid, I had found out that my mom had epilepsy and was in a family of 6 , so I had 2 other brothers and a sister, I was getting some kind of a strange symptoms of that something happening to me here and there, I didn't know what was going on, anyway as I was after a little while into having it happen, I thought I had what she had, now you would would think that this maybe of inheritance, ok , but I was diagnosed with after I was sleeping on the couch and one day the next day in the morning, I had two police officers in the house, they were asking my mom and dad question about me and such what was going on with him, the one police officer said I think he might be on drugs, well after that my parents took me to the hospital where was diagnosed with epilepsy, I been with ever since, so I was the only one that had it, everyone else in my family didn't, and I'm just wondering you would think that it was because of my mom and what she had, but my question then is, if that's the case, how come the rest of my family don't get it but I did, I understand what the police officer had mentioned, but he was just doing his job, I had an idea of what I had and didn't know how to bring it to my mom since she had the condition also, I asked myself a? , how do I do that? I found out about it after the diagnosis but before I wanted to tell but didn't know how and scare her, so I understand what you are thinking about and such, similarly, so I didn't blame my mom for what I have, i learned to accept and live with, my perspective on this question, my opinion