Historical socioeconomic factors, things that aren't fixed within a handful of generations

Also culture, socialization, and community structure (which may also be the result of historical events).

“Socioeconomic factors” by themselves have limited explanatory potential. Even the poorest Canadian reservations are wealthier per capita than India is now or China was a few years ago. But the homicide rate among indigenous Canadians is about double what India’s was in 1990, and triple of what India’s is today. It’s almost 20 times higher than China’s homicide rate.

Genes.

For all sorts of reasons?

British Pakistanis and British Hindus look basically the same, especially to a naive native European, but the groups are internally different enough to be on the opposite ends of the British societal ladder in all sorts of attributes - education, wealth, crime rate etc.