HAVING large families should be frowned upon as an environmental misdemeanour in the same way as frequent long-haul flights, driving a big car and failing to reuse plastic bags, says a report to be published today by a green think tank. The paper by the Optimum Population Trust will say that if couples had two children instead of three they could cut their family's carbon dioxide output by the equivalent of 620 return flights a year between London and New York. Full coverage: Climate change in-depth John Guillebaud, co-chairman of OPT and emeritus professor of family planning at University College...