I'm asthmatic and allergic to dogs, you insensitive clod! And furthermore, my dad had a dog when I was a kid.
I personally blame my asthma on my mother smoking until she found out she was pregnant, and my father smoking until shortly before he died, including all throughout the pregnancy, in the car, in the car after I was born, etc etc. There's no family history of it on either side. But of course, there's no way to know. It's convenient, though, because one parent is dead and I don't talk to the other one.
And no, I am not passing on these genes. They're just not that fantastic. Good enough for my purposes, but they could be better even there. If I weren't asthmatic, I likely also wouldn't ever have become overweight.