Yet another negative effect is the 4-2-1 problem. In China, a child takes care of his or her old parents (and grandparents, if they are still alive) when they become an adult. In the times when there were many children in a family, this was not an issue; however, nowadays a grown-up singleton must take care of two older parents, and four grandparents – including financial support, health care, and so on. Considering that by 2050, the amount of old people (65 years old or more) is expected to be more than a quarter of the whole population of China, it is not hard to imagine the excessive burden of family responsibilities that each singleton will have to face (IO9).