My first thought on the Congress diagram was, what if they *completely* reflected the country, but that's silly, of course - some attributes do affect fitness for office. (For example, level of education maybe; age, certainly, at least inasmuch as a five-year-old Senator most likely wouldn't be up to the job, even though there are five-year-old constituents.)

But what about other things such as blood groups, hair and eye colour, sexual orientation, marital status, or veteran status? (Or pregnancy status?)