I think you've been here long enough to know that a phrase like "automatically and without exception" is likely a poor interpretation of what the parent poster meant with "standard household activity".

I was born and raised in Florida. In Miami I lived in a 1950s house designed w/o A/C and with effectively no insulation. In Tallahassee I lived in a 1970s house designed for A/C. But we didn't have money, so we didn't run the A/C unless it was nasty hot.

The differences were remarkable. For the same temperature and humidity, the Miami house was much more comfortable. The vernacular architecture of high ceilings, open crawlspace, and massive amounts of windows meant there was still cooling with any sort of breeze.

With the Tallahassee home, the building was designed to insulate, to keep the A/C power bills low. The windows were small, there wasn't much cross-breeze even with all the windows open.

A/C systems include dehumidifiers, and the building has a vapor barrier to prevent the high outside humidity from coming in.

But w/o the A/C's dehumidifier, standard household activity like breathing, cooking, and showering raise the inside humidity more than the outside, with a slow rate of equilibriation.

We finally kicked on the A/C when, among other things, yes, mold started to form.

Of course 'lifestyle choices impact details like heat and humidity'. So does architecture, as I just pointed out. But btbuildem said 'standard' and 'usually'.