Is it normal to feel like an outsider?

I'm Mexican but raised by polacs in foster care. My birth parents were gamblers and swindlers so they couldn't raise me properly. They gave me up at the age of one. Anyways I haven't met them til I was 23. I was desperate to know them so I asked my mother on information and they gave me what I needed to know. When I found them mix emotions were going through my head. Apparently they were looking for me too. And after they explained why they couldn't keep me we grew a strong bond. I have three other siblings and the resemblance is scary.

So it been 12 years later and we are one big happy family. I still am very close with the people who raised me. We go out for lunch once a week. I love them with my whole heart dearly forever and always. Anyways my real family is so Mexican or makes me upset. They all speak Spanish except me (obviously due to the fact I wasn't raised by them. I tried taking Spanish classes but never understand it properly.) They like different things from me. They know English but when they do use their native tone I can't help to feel like they are bad mouthing me (I know they not). Our styles of food are different and all this other stuff. I really feel like an outsider and I don't know what to do. This really make me feel depressed and I don't want to tell them about this. They might think I'm insane. Is it normal to feel this way?