BEIJING — The mother of China’s prime minister was a schoolteacher in northern China. His father was ordered to tend pigs in one of Mao’s political campaigns. And during childhood, ‘‘my family was extremely poor,’’ the prime minister, Wen Jiabao, said in a speech last year.

But now 90, the prime minister’s mother, Yang Zhiyun, not only left poverty behind — she became outright rich, at least on paper, according to corporate and regulatory records.