Earlier quoted context omitted.
Oh, and he has perfect pitch. Can tune stringed instruments without a reference, was employed to do so for some summers. It was something he could do, from a very young age. Not apparently learned. Not learned by most of his cohort at music school, so I'm guessing most likely something born with. If there is a distribution, then we have to task to explain that. Reasonable to call it genetic? Why not?
I don't know what you mean by "not apparently learned". Even with genetically inherited perfect pitch, the skill has to be "learned" (IE, presented with note labels). Nobody has the ability- without training- to tell you the frequency of a note. Genetic (in this case) doesn't mean "born with the ability", it means "predisposed towards greater ability after training"). Personally, I'd start with the strong observation…
The idea that there is an 'absolute' involved indicates a reference of sorts, that is what makes it absolute. Labelling notes will distribute them along a bell curve and the dead center of that bell curve may or may not be the exact note. People with absolute pitch are able to do this exactly and that is what makes it interesting, that implies a reference to some standard, presumably one that they have internally. A tuning fork is such a standard, as are other mechanical oscillators with a high degree of repeatability.