If you have never had a relationship with your father would it be okay to have a relationship with his family?

My mother and father divorced when I was a baby. I did visit him some as a toddler. Then for some reason when I was around 2, it seemed as though he just dropped of the face of the earth. I don't know what exactly happened, but I never got a birthday or christmas card from him or any of his family. They never called or anything. I meet my half brother when I was in high school. My grandmother and mother had told me that my dad had got married and had more kids and told me their names. So I have been keeping in touch with my half brother and sister for the past few months on facebook. My half sister told me that she was working at a new Bar & Grille in town, she told me to come there sometime. I went there tonight and found out that our uncle actually owned it. I met some of my cousins and aunts and uncles for the first time. They want me to come to there house and everything. I feel a little weird because I don't know them. I know they are my family but they never called or sent me any letters or cards or anything. I don't know what I should do. What would you do?