I don't know what kind of molds you have in Texas, but here in the humid northeast/mid-Atlantic area, pretty much all houses are susceptible to mold, as poster #20 notes. I believe most of the molds you find here are completely benign in the doses most people get.
Where you run into trouble with toxic molds, I suspect, is in these highly insulated, air-tight houses built since the oil crisis in the '70s (and in older houses remodeled to be "energy-efficient.")
Older houses that leak air like a sieve are healthier, if less energy-efficient.