yes! they have a one child policy, which means that each family is only allowed one child per group. if there is an instance of twins, or a couple having more than one child, the 'extra' child is forcibly given up for adoption. this is a big reason for an increased number of the adoption of Chinese children by people of other countries
Derek54 is right but there are small exceptions to that law such as second child is allowed when both the parents are the only children of their parents or in case of rural couples whose first child was a girl.