It's a side-effect of cultural norms going back thousands of years. In marriage, status is a key factor, and the parents of both partners are the main decision

It's a side-effect of cultural norms going back thousands of years. In marriage, status is a key factor, and the parents of both partners are the main decision maker whether to allow a marriage or not. Status wise: A man marries a women of lower status, a woman marries a man of higher status -- that's more likely to be approved by both sets of parents. (And parental approval is important in Chinese families) Which means, there's talented, very smart women in China who are struggling to find suitable husbands, because they are equal to high status men. And those men are looking for women with less status. The Male leftovers tend to then be at the bottom of the status chain, because there's no lower status of women to marry. So there are loads of rural areas and villages where women have moved to the city, and men remaining have no viable marriage prospects. (This is the segment negatively affected by one-child policy)