Why is my kitchen so humid?
It may be an addition built on a crawl space and not a real basement.  Buildings on Crawl spaces tend to be more humid.  Single pane windows condensate alot more than double pane which will put moisture into air.
Run a dehumidifier during colder months and A/C during warmer months to pull moisture out of air. 
If you have a crawl space tell me about it. Type of vents, Flooring, insulation, how much lower than grade is it? Is it damp all time? Just after rains?