I didn't know I was related to my boyfriend at first . My grandma is his grandpa's sister. His grandpa is dead and has been since before I was 3 years old . His mother claims another man as her father for the most part so we never met. Is it weird? What should I do?

Go for it.
Just like the constitution... the framers couldnt have possibly meant what was written. No, its a living, evolving list of... suggestions only.