You're going to have to be very specific about what you mean by "homogeneity" to tighten up this argument. Other comments farther down-thread precede mine in time, but I thought I would group some discussion of some of the disputed factual points here, because I agree with a thoughtful earlier comment that "This is a meme that should die, because it isn't based in any fact, but is mere speculation." Show the work if you want us to believe that this is a significant issue.

Looking at a list of countries by population,

http://en.wikipedia.org/wiki/List_of_countries_by_population

I am reminded that Sweden is the most populous Nordic country and that the Nordic countries rank about the same in the world rankings as Singapore, an amazingly multi-ethnic country.

It is hard to remember anymore that Singapore was a very, very poor country when it achieved independence (after being expelled from the Federation of Malaysia in 1965). Singapore was settled earliest by ethnic groups similar to those in current Malaysia, with a big influx of wretchedly poor agricultural laborers for plantation labor during the British colonial period. It was not expected in the pre-independence period (which extended into my lifetime) that Singapore would ever be prosperous. (You can watch a videotape of the movie Saint Jack, which was filmed in Singapore, for a reminder of the poverty in Singapore as recently as in the early 1970s.)

But the early leadership of independent Singapore strongly emphasized effective generally available primary education (without at first even making school attendance compulsory) and studied the best international examples of sound textbooks and effective teaching practice.

http://www.merga.net.au/documents/RP182006.pdf

School pupils in Singapore from my generation (born in the late 1950s) grew up in a country that was extremely poor (it's hard to remember that about Singapore, but until the 1970s Singapore was definitely part of the Third World). People from Singapore are so ethnically diverse that Singapore has four official languages from four different language families. All the school pupils were educated in a foreign language (the language of schooling in Singapore has long been English, but the home languages of most Singaporeans are south Chinese languages like my wife's native Hokkien or Austronesian languages like Malay or Indian languages like Tamil). Official surveys by the Singapore government

http://en.wikipedia.org/wiki/Demographics_of_Singapore#Langu...

show that as recently as 1990, Singapore had no majority language among the various languages that people speak in their homes, and the plurality language category was category including more than one language, none of which are even one of the offical languages of Singapore. Yet young people growing in that generation, going to school in a language they generally didn't speak at home, received very thorough instruction in mathematics and science and other subjects.

Today Singapore is prosperous, and one set of projections suggests it is on track to be the richest country in the world on a per-capita basis by 2050.

http://globalpublicsquare.blogs.cnn.com/2012/08/15/singapore...