Mold is a very large subject and something I can only touch on here. First of all I will say every home has some mold. Secondly mold can produce serious side effects in people but it should not be feared. Sometimes mold is portrayed as a silent killer but this is more for media effect then fact. I recommend following some basic practices that will keep mold levels normal within your home. First of all be aware that mold will only grow if it has a source of moisture and a material to attach to. For the most part moisture levels below 16% do not provide a good enough environment for mold to thrive. Secondly surface materials such as drywall paper and carpet are much more likely to grow mold than a concrete wall so if you see moist drywall think mold is possible and do all you can to dry things quickly. In General controlling moisture controls mold.