sentences:  They acknowledge the old 1960s argument that abortion may prevent the birth of "unwanted" children, who would have relatively small investments in human capital and a higher probability of crime.On the other hand, their research suggests that liberalizing abortion rules correlates with an increase in out-of-wedlock births and single parent families.In turn, they argue that this increase in single parent births implies the opposite effect on investments in human capital (i.e., average investment per child decreases under their argument).