Due to the country's one-child policy and a cultural preference for boys, "The Chinese Academy of Social Science estimates that by 2020, 24 million Chinese men will be unable to find a wife...Some believe that impact is already being felt as single Chinese men, referred to as 'bare branches' because they will not bear children, appear as an increasingly high risk group," says Al Jazeera. "Lena Edlund, a professor of Labour Economics at Columbia University, says China's gender imbalance is partially to blame for an increase in violent and property related crimes. 'Unhappy, frustrated people are by themselves a problem for society since they are part of society. The problem gets magnified if those individuals act in anti-social ways. Men without partners and children are a risk group in this respect,' she says."