I knew a family who came from an extremely spotless house and almost everything almost killed them.
I dunno about the asthma, my granddaughter has grown up in a dusty house, she’s had pigs, dogs, cats, goats, horses and when she turned 13 started up with the asthma. She’s allergic to all animals and she loves them.
She has ended up with a hamster,she is allergic to him but she just holds him in her hands and then washes them immediately. Her brother cleans the cage and he lives in her brother’s room.