Attic mold is not likely to cause a health concern for the family, but it can damage your rood.  In most cases, we are able to treat attic mold that hasn't started to cause rot of the wood sheating in the attic.  

As you might know, mold is a growing fungus-type plant.  Mold feeds on wood, paper, and cardboard.  So, given enough time, mold can destroy wood.  But, the attic is a separate air space from the house.  This menas that the mold spores are unlikely to affect the living space of the house.

Basically, mold in a house is never a good thing.  It has a bad smell, sends out spores that aggravate respiratory conditions, and may produce mycotoxins that adversely affect health.  And, mold gradually destroys the wood it is attached to.

Finally, no bank or homebuyer will accept a house with an active mold condition.  If you want to sell your home soon or someday, it is best to treat the mold problem as soon as possible.