If you've grown up not really trusting your parents and feeling like they don't treat you right, it makes sense your brain is trying to find a reason for why you feel so different and out of place.
#Felling Adopted
split cape
But feeling different, having different interests, or even people saying you don't look like your family doesn't automatically mean you're adopted. A lot of people feel like they don't fit in with their family, especially if there's stress, trauma, or you just weren't understood growing up.
The part that stands out more is that you don't feel safe with them and feel like they make fun of you or don't respect you. That alone can make anyone feel disconnected and alone, even during stuff like Christmas when you're "supposed" to feel happy. That feeling of missing someone or something important is usually more about not having that emotional connection, not necessarily that there's another family out there.
The nostalgia thing and feeling like you belong somewhere else can happen when you've been feeling disconnected for a long time. It doesn't mean it's fake, but it doesn't automatically mean it's literally true either.
Also, even if someone is adopted, it doesn't mean they weren't wanted. If anything, it usually means the opposite. But honestly, I don't think this is really about adoption. It sounds more like you've been feeling disconnected and not understood for a while.