Is it normal that i don't get sentimental about my childhood and family?

I don't like looking at old photos, movies... listening to my parents talking about us as kids, etc. It all leads to me, the slow, stupid one being compared to my sister, the quick, smart, fun, good-looking one. (she's also a nasty, evil bitch) On birthdays, my mom would even describe our behavior in the womb, and how she already knew our personalities before we were born. Basically I was completely still -- like brain dead or something. I stopped going to family events a long time ago for this reason.