A well insulated (air tight) house does make it easier to keep some humidity out with a ventilation system with an ERV (Energy/Enthalpy Recovering Ventilator).

A well insulated (air tight) house does make it easier to keep some humidity out with a ventilation system with an ERV (Energy/Enthalpy Recovering Ventilator). It basically has a membrane which keeps humidity on the most humid side. So it keeps indoor air dry in humid summers, and humid in dry winters. I have one, and it helps keep my house a lot more comfortable in summer, reducing the need for a/c to maybe a couple of weeks a year.