"Then, of course, most americans are not the progeny of convicts."
Actually you may be onto something Cxim, What with America's history of settlment by the pilgrims, & those escaping religious persecution & settling in Pensylvania.
Whereas here in Oz, all the colonies, except one were penal colonies. Plus the times were different, later Georgian & Regency Britian was very unreligious, relative to the perid that the British settlements in North America occured. Then just as the convict era was ending, the goldrush was beginning.
However most Australians have either no convict blood or very little convict blood. Plus there's been huge numbers of immigrants from the Mediterainian countries, Eastern Europe & THE Middle East, since the end of WWII & from the 70's many have come from Asia (plus thousands of Indian refugees from former British East Africa settled here too), making Australia the most multicultural place in the world.