Daddy who?

My father has never been apart of my life. Ive met him a couple times, but thats about it. Not just him, but that entire side of my family has never really had anything to do with me. No birthday cards, no invitations to family reunions, nothing. I can remember running into my aunts or my grandma from time to time in the grocery store. They would speak, ask how i was doing, and then give me $20. I guess it was guilt money for never being in my life. I have a couple cousins my age on that side and all thru out grade school people never even knew we were related because we never interacted at all. I have nothing against any of these people. As a matter of fact, I feel nothing for them. Its like that part of me is just non-existent. Were related in name only. One person I really did care for though was my great grandmother. I would walk to her house from time to time and just sit with her and talk. I really felt that she cared for me. I miss her to this day and wish I had spent more time with her so id have more memories of her. Despite the common belief that people in my situation grow up to have "daddy" issues, (Anytime I tell people I dont have a dad, they give me this sad "I feel so sorry for you" look) I think I grew up very well. My mothers family loved me unconditionally and they gave me everything I ever needed physically and emotionally. Sometimes I do wonder though what it would have been like to know that other side of me. I have all these aunts, uncles, cousins, maybe even brothers or sisters out there that I know absolutely nothing about. It would be nice to have a connection with these people. To have shared memories of growing up together. Celebrating birthdays, holidays, family get-togethers, and so on. At 27, its a little too late to try and bridge the gap between us. They've always known how to get in contact with me. Im even facebook friends with a few of them and still to this day, besides the occasional "Hey, how are you?" message, there has never been any form of reaching out. I guess what id really like to know is why. Why have they never treated me as apart of the family? Is it because for some reason they dont like my mom? She did have me when she was 18 and as far as I know, im his only child. So maybe they disapproved of him getting a girl pregnant at a young age. Maybe even some event happened before my birth that caused all this? I dont know.