Our home is a little over two years old. First I would check your chimney and heating system.
Fossil fuels give off tremendous amounts of water vapor.
Have that checked first. Seond source I would check is the basement and crawl spaces. Is there an uncovered floor or a moisture problem in any of these areas. A dirt floor in a crawl space will greatly add moisture to teh house. If the basemnt or crawl space is damp, be sure your gutters are working well, and the ground around the exterior slopes away from teh home.