Is abuse a choice

Abuse should be viewed from the victim's perspective. It doesn't matter why the abuser abuses or what's going on in their mind. What's important is the welfare of the victim and how they feel.

I think a very few genetic or neurological issues can cause personality changes like this. Those are able to be diagnosed and potentially treated.

Everything else is probably related to unresolved trauma or lack of personal control.

It terms of perpetuating it ,sometimes maybe/maybe not. However when it comes down to accepting the abuse.

Yes there's a choice

Depends on the illness. If a person is experiencing psychosis and thinks their household member is a demon or something, you can't really blame them.

But if they just have a personality disorder or disability, it's not really an excuse.

It's never that simple.

It's hard to say. I chose to abuse my ex cos he deserved it but every relationship is different

It's never an excuse, but calling it a choice isn't accurate, either. Abuse always comes from a place of pain, and that pain leads to something akin to paranoia.

like you said, unless there is a serious mental illness then it is 100% a choice.