Can exposure to cat urine cause asthma for life?

[rockstar82]

When i was younger, my parents got divorced and my dad got remarried. My mother ended up being a crazy cat lady and ended up with like 25 cats. Our house smelled horrible. I was used to the smell at the time ( i was just a kid then).

My father got re-married, and ended up having another child with a new woman, after the original 3 kids with my mom. When i would go visit my father, me and my 2 siblings would smell like cat urine.

This lasted for approximately 1-2 years.

At this same time my little half brother was just a baby.

My stepmom smoked while pregnant with him. And she continued to smoke in her washroom in the house on occasion.

My mother ended up losing her place and we went to live permanently with my dad.

My little brother had developed bad asthma. He continued throughout his childhood and early teens to suffer from bad attacks, despite us even owning any pets at all for the next 15 years.

My stepmother continues to blame my mother for his asthma (even though she smoked while pregnant and occasionally smoked in the house).

My question is,  is she right? Can exposure to cat urine (not living with the cats, just smelling them on our clothes half the time) actually cause the permanent asthma condition and continue to give him asthma for the rest of his life even years after the cat has been removed? Or was it more likely the second hand smoke and smoking while pregnant?