Here is the abstract of a paper I have not yet read:
In this paper, we analyze the extent to which market forces create an incentive for cloning human beings. We show that a market for cloning arises if a large enough fraction of the clone’s income can be appropriated by its model. Only people with the highest ability are cloned, while people at the bottom of the distribution of income specialize in surrogacy. In the short run, cloning reduces inequality. In the long run, it creates a perfectly egalitarian society where all workers have a top ability if fertility is uncorrelated with ability and if the distribution of ability among sexually produced children is the same as among their parents. In such a society, cloning has disappeared….