I’m at fault?!?

I’m 26 years old and when I was 2 I started living with my Dad’s parents. They are the only parents I’ve ever known. My parents were either never a couple or split up not long after I was conceived. My dad married someone a month after I was born. I’ve never had a relationship with either parent. I saw my biological mother every few years and then the last time I saw her I was around 10. She’s tried to contact me through Facebook only because I have 2 kids now. She moved to another state when I was younger. I saw my biological father only because he wanted something from his parents. He never really acknowledged me when he was around. My biological father tells everyone that I won’t have anything to do with him even though he’s had 26 years to be a dad to me, but has never tried. I invited him to every birthday party, school play, church play, anything to involve him and still he had an excuse. It makes me so mad that he puts the blame on me and gets mad because I call my grandparents my real parents