Are mold spores in every home?

Yes. Spores are in outdoor air across Adams County and they come inside on clothes, pets, and open windows. A lab will always find some. The question is whether the house is amplifying them because something is wet.

That is why an indoor sample without an outdoor sample from the same day is weak evidence. Matching the yard, in a dry house, is ordinary. A wet wall with a water-damage genus indoors is not.