It's definitely not just for mothers. I don't have that kind of feeling at all for my mom, but if my dad wasn't here, I'd probably kind of go crazy missing him. I think it depends on the person, how they treated you, those kinds of things. It's just, usually, moms are way more lovey and caring and stuff so it's easier to attached to them. Except mine because God no
You're totally allowed to miss her, btw, even if your siblings don't. You don't feel what they feel because your memory of who she was isn't the same as theirs and that's okay.