[Mr_Minderbinder]

> Example: The average height (a trait with very high heritability) of Dutch men is...

I would not give too much credence to the various figures often given for the average height of men and women in x country without careful research, since they have highly variable degrees of support.

For years I had heard repeatedly that the average height of a man in Indonesia was 158 cm or 5ft and 2 inches. This seemed so absurd to me and provoked enough scepticism that I eventually attempted to track down the source of that figure. It turned out to be from Wikipedia and the citation was a study that measured the heights of the elderly yet all of those repeating that figure neglected to mention, or were in all likelihood entirely ignorant of, that detail. I am similarly sceptical of some of the claims made about the average height of the Dutch, the subject of which seems to be a particular favourite among height myth-mongers.

With respect to young adult men I have found that figures based on measurements obtained as part of fitness screenings for mandatory military service are the most reliable due to their large sample size (at least an order of magnitude larger than the largest academic studies) and overwhelming lack of selection and sampling bias. A minority of nations have such systems and fewer still publish the data obtained in public. Yet even this would not answer the question for the whole population.