Nancy Folbre discusses the findings of a recent paper on the economics of taxes and babies:

Over all, parents pay less in net taxes than nonparents do — until the
future net tax contributions of their children are taken into account.
 These more than offset the difference, leading the authors to conclude
that the average parent contributes far more than the average nonparent
to net taxes — a difference of more than $200,000 in 2009 dollars
(discounting future contributions at an annual rate of 3 percent).