is it weird if twin brother and sister are super close?

My twin brother and I are 17 and just the best friends. Ever since we were born we did EVERYTHING together, we have the same group of friends and we just tell each other everything. Of course we fight sometimes but we're best friends we couldn't do anything without the other person.
Now people commented weird things under our instagram posts like as if they think we're doing something wrong it's just weird and super disgusting like he's my twin brother- if I was a boy I'd be him like people don't get it he's the closest person to me and it's the other way around if we'd be more related to each other we'd be the same person.
What do you guys think? Is it weird that we're just like that?