Think you know where the candidates for New York mayor are coming from? Think again. With less than 90 days to go before Election Day, the candidates are all migrating toward the political center, dropping old positions and adopting new ones, freely copying one another’s policies and style along the way.

The attacks in the New York City mayor’s race may have veered into the personal, but they also reflected a larger debate on who should benefit from government regulation of housing costs.