Disclaimer: I have seen this correlation for quite a while, and I am genuinely curious about the possible reasons behind this correlation. By no means do I intend my blog post to come across as discriminatory, offensive or extremist. If, out of my gross negligence, this blog post comes across as so, please do not hesitate to explain my mistake (in the comments section).
Look at the results of IOI 2022 and you will see that the Chinese team dominates the ranking. The same can be said about IOI 2021, and (to a lesser extent) IOI 2020.
I think the reasons for the dominance of China's team are rather plentiful: a huge population pool of potential CP-ers, a sizable middle- and upper-class, and, perhaps, a culture and/or school system that encourages academic achievements, including competing in CP contests.
But look a bit further down the IOI 2022 ranking and you will see students representing the US and Canada who seem to have Chinese heritage. (Please do not forget the disclaimer at the top of this blog post.) The same can be said about IOI 2021, IOI 2020, IOI 2019, etc. I'll look at a few countries exhibiting this interesting correlation.
For many years (to be more precise, 23), the US team has obtained at least one gold medal (you can see this here). From 2008 onward, the US team has had at least one gold medalist who is of Chinese ancestry. In fact, a significant part of the US teams seems to be of Chinese heritage; by "significant part" I mean two or more students per year (Again, you can check it here and scroll through the years to see the US teams). If the majority of the US' population was of Chinese ancestry, then this trend would be self-explanatory. But the US' population is mostly of European ancestry (see here) and so this correlation may demand a more complex explanation.
To further show my point, let's look at Canada. The correlation here is not as obvious as in the US' case, but you can still see that, for many years, the strongest student in Canada's team has been of Chinese heritage (see here). You may say that this is merely a coincidence because of Zixiang Zhou's outstanding skills and, while I find some truth in that, I recommend taking a closer look. Even before Zixiang Zhou's meteoric rise, the strongest CP-ers in Canada's teams often were of Chinese ancestry (look here, before 2019) and a significant part of Canada's teams are of Chinese origin (see here and scroll through the years).
Another example is Australia. I'll be honest, this time I am not really sure whether that many people out of Australia's teams are of Chinese origin, but it is likely that Australia's teams have had for many years at least one person of Chinese heritage (see here).
New Zealand's case is somewhat similar to Australia's (you can see the delegations here).
You may see this correlation also at UK's teams, but it is too weak (in my opinion) to have it really count as a supporting example.
This trend seems to be shown only by a few large and developed English-speaking countries (for example, I haven't seen it in Germany or France's teams).
So, my question is: Why? Why are so many strong CP-ers of Chinese ancestry? Is it a US- and Canada-specific thing? Or is it about the CP-ers backgrounds? Or maybe something else? I would be interested to hear (or rather, read) your takes.