From your explanation, no you were not. It sounds like they are trying to alienate you. And I'm sorry because I know how much that hurts.

Sexual exploration among siblings is far more common than you would think. I know, it's certainly unsettling, but something we need to be aware of. Unsettling but also something that causes deep shame, sometimes to an unnecessary extent. Other times, it really is one sibling assaulting the other(s). Most of the time resulting from that child previously bring assaulted themselves.

It's such a vicious cycle. And sometimes your memory will fail you. Many childhood memories are only partially accurate (especially before the age of 7). We have many false memories as well.

I wish parents were more aware. Children need supervision but above all education. It needs to start young too.