If we find out he's our brother, does he have any rights to the estate?

My father passed away 5 years ago in 2012. He did without a will so my brother was the executor. We just finally settled the estate the end of 2016. April of 2017, someone came forth after doing an ancestry search to say they think they may be our brother. They asked if I would do a DNA test. I don't want to do anything until I find out my rights regarding my father's already settled estate.