How do people feel about characters calling each other "bro" or "sis" to reinforce that they are siblings?

I've read quite a few mainstream novels lately that employ this technique and I wondered what the general consensus is? I'm not saying there are not real life siblings that call each other by those terms, but for me sometimes in writing it feels a little bit forced and unnatural. I'd love to know what other people's opinions are on this, if you use it or don't use and why?