Why are daughters so special to fathers? What about sons?

Aren’t sons special too?
I mean my dad says all of his kids are special but daughters are precious to fathers. My sister is married, has her own kids but dad is still protective of her but treats my brother in law like his own son. My dad is especially protective of me. I don’t always see things other people see, I’m autistic and I was told that I can’t defend for myself because I let people walk all over me, I never stand up for myself and let’s people yell or talk to me like that any kind of way and I end up being resentful and angry inside.