All windows except the bedroom windows were replaced with the same brand at the same time back in the late '90s
The side by side double north facing windows in our kitchen get condensation buildup in the summer sometimes depending on outside humidity. The also north facing single dining room window and side by side double windows in the living room never have yet. My guess is the kitchen window seals no longer seal well and since there is a AC/ heat vent directly above and center of the kitchen windows, the cold AC air blowing directly on the window causes any humidity vapor to condensate on the colder glass.
