Mold can be a major health risk to you and your family, especially so if someone already has a sensitivity or allergy. It is also possible that you could develop an allergy from long term exposure to mold, so it is definitely in your best interest to take care of the problem as soon as possible. Mold grows where there is moisture and poor insulation, so you need to take care of areas of your home that present ideal growth conditions for mold.
You should definitely air out your home regularly, but on top of that, you need to have proper ventilation, especially in high-risk areas such as your bathroom. If your bathroom fan isn’t working well enough, be quick to replace it.
You should not leave towels bunched up on the floor for any amount of time, and in some climates, it might be necessary to squeegee your shower dry after you are done with it.
You should take care to fix any leaking fixtures as soon as possible as well.