I should also clarify that resonance is a function of size and microwave covers so many wavelengths it is nearly useless as a term. A single h20 molecule is not resonant at wifi frequency, they can't interact. Your balls, hopefully, are big enough to be warmed if exposed to enough energy at wifi frequency. Again, legal omnidirectional wifi won't do it even if you spent all day with the antenna touching your balls.
Discussion
Yes I would expect legal power from a home WiFi set up to remove all concern. There are engineers and hobbyists that reach much higher power and directionality and so far I haven’t heard those groups having a greater incidence of cancer than the general population. It’s like Agriculture chemicals it’s the farmers that have the most exposure. If a chemical has a harm, they should experience it before anyone else.