Well having read this here is my informed opinion on the issue... informed because I’ve studied biochemistry and genetics for well over ten years, so even though I might not be a vet, I do have some idea about things…
My opinion odds are Cryptorchidism is due in a good measure (I would say 90% of cases) to environmental factors, having little to do with either parent. For one thing it is a process so complex that things are bound to mess up more because of mechanical (ie the environment) or circumstantial (a little infection in the wrong place at the wrong time… so small it would go undetected, or perhaps a nasty insect bite) reasons, rather than genetic ones. There is actually some evidence for this… because a quick little search on the topic has revealed that in humans (who of course are not dogs)
The incidence in humans is: 1/3 premature male births, 1/30 live term male births, 0.8% after age 1.
Interesting because it shows that it is an environmental factor (prematureness) rather than a genetic one which results in an increased risk for cryptorchidism.
Epidemiology: all humans affected, no geographic propensity.
This too is interesting because it shows that genetics is NOT a major factor. This affects all humans uniformly, regardless of race, nationality or gender… er… ok maybe gender does matter in this case
In dogs it would be tempting to ask a vet if some races are more prone to cryptorchidism than others. If it is not the case then one might assume that no genetic factor is involved (with the genetic diversity in the different dog races, such a thing would not have been homogenously distributed) Unfortunately even if there is no “direct” genetic effect, different dog races would be affected differently by cryptorchidism because things like for instance pelvic morphology would be a determining factor (and this morphology is in fact partially genetically determined)
Right ok so this would be anathema to just about most people (Because dog breeders operate on the basis that cryptorchidism is genetically determined and thus do not breed males who do not have both testicles… but unfortunately evidence (at a glance, I did not do an in depth study so I’m open to suggestions) tends to mostly environmental factors.