My relationship with my father is strained

Warning: this will be a long post.

Anyway, to start off this post, you need to understand some background detail. So my birth was an accident. My parents were dating but my mom ended up pregnant after several months of their relationship. My mom was newly immigrated to the US, 22 years old, had no family in the area and broke. My dad was 30 and was in the middle of graduate school in a prestigious university here in the US. He comes from a relatively well-off, upper middle class, middle eastern family.

So anyway, my mom gets pregnant and chooses not to tell my father of her pregnancy due to fears that he may try to take full custody of me - because of his ethnic background and how strong they are about their culture, and because she knew he probably wouldn’t want to marry her due to the cultural difference between the two of them. So when my mom finds out of her pregnancy, she cut off all contact she had with my dad. I grew up not knowing my who my father was. It wasn’t until I was 12, when my mom had a change of heart and decided to try to find him and tell him of my existence.

She does end up finding him and she confesses to him. My dad, understandably, is wary of the whole situation and assumes she’s just contacting him for the money. My bio paternal grandparents agreed to undergo a DNA test, and surprise, i am biologically their grandchild. So at 12, i finally got to know my dad. I saw him for the first time at 13 when i visited his side of the family in the west coast.

Ever since i’ve known my dad, our relationship has always been pretty strained, and understandably so. I’m 24 now, and we’ve always gotten along well, but we never had a close relationship like i would’ve like to had. My dad never really calls me, only texts me through WhatsApp about once a month. Never went to any of my graduations. Never said he was proud of me or has ever initiated an “i love you.” Never really tries to get to know me on a personal level. Anytime we spend time together, he just talks to me about how i’m doing in grad school and how my career is going.

The reason i’m posting this now is because i’m currently visiting my paternal side of the family on the west coast. I see how my dad treats my half siblings (7 years old and 1 and a half), and it’s like night and day compared to how he is with me. He is so sweet, loving, and caring with them. And the amount of attention they get. With me, he doesn’t have much of a conversation with me other than small talk and rarely acknowledges me if we’re in the same room. Earlier today, we were celebrating my step mom’s birthday and we were doing pictures. My stepmother, dad, and half siblings got up to take pictures. My stepmother was the one to ask me to be in them and include me in the pictures with them. It breaks my heart, even as a 24 year old grown ass man.

Has it always been idealistic of me to expect a close relationship with my dad? Has the damage been done from trauma of my father not being able to bond with me as a kid? I can’t tell if it’s just awkward for my dad still after all of these years and he just doesn’t know how to bond with me or if he secretly resents me.