Cultural assimiliation

As a migrant to Australia, I am constantly reminded how quickly the migrant children of various races adopt the local culture. Everyone who comes to Australia at a very young age, or who is born here, invariably speaks with an Aussie accent, behaves like an Aussie, and thinks like an Aussie. This happens regardless of whether the child is of Chinese, Indian, Vietnamese, or even Middle-eastern descent.

I find this very intriguing. My grandparents migrated from China to Malaysia, as do most of the grandparents of my peers. In Malaysia we held on very strongly to our Chinese culture, in terms of religious practice, customs, speech, and schooling. Even the Indians, who make up less than 10% of the population, retain their Indian heritage thoroughly. So why are the migrant children in Australia able to assimilate so quickly?

On the same token, the Chinese who went to Malacca emerged with a totally different culture - the Baba Nonya culture, which is neither Chinese nor Malay, but a curious blend of both.

What makes migrant group assimilate or not assimilate into the local culture? Is it spontaneous? Is it random? Is it the government policy? Surely this makes an interesting subject for any anthropology student.