Do dog lovers have fewer children? George Orwell thought so. Britain's "cult of animals", he complained, had contributed to a falling birth rate. Writing after the Second World War, he noted: "Britain today has a million and a half less children than in 1914, and a million and a half more dogs." His theory may have been eccentric, but his fears about birth rates were widely shared at the time.
Today many governments worry about such things and some try to make a difference. France, Estonia and Singapore set demographic targets, Australia has a pro-natalist policy, Japan sponsors dating agencies and Nordic countries help families. Yet in Britain, the home of Malthus, population policy is viewed as nanny-statism. Why?
Other countries, of course, have their own experiences. France is responding to angst over national identity; high immigration levels concern Australia and Canada; and Italy and Japan are worried by the economic implications of an ageing population.
Such concerns can appear less pressing here: our fertility rate is relatively high, the population is set to rise to 69 million over the next 50 years, and migrants swell our labour market. But things are not as rosy as they seem. Fertility may not be high enough: if it stays at current levels, Britain faces serious pressure on public finances by 2050. If it falls, the results may be severe.
Other forces are at work, too. In 2004 seven million people lived alone, nearly four times more than in 1960, and by 2021 there will be 8.7 million single-person households in England. This threatens to exacerbate poverty and inequality, amplify care needs, transform housing requirements and intensify environmental problems.
What's more, our "demographic aspirations" are not being met. Hundreds of thousands face barriers preventing them from having the children they desire, and a significant proportion of those living alone do so against their wishes.
Britain is not France; we don't need baby bonuses. But we can't afford to ignore this. We could, for example, address fertility by helping people balance work and family life, with better childcare and more parental leave. It may not feel very British, but Orwell would have approved.
Population Politics by Mike Dixon and Julia Margo is published by IPPR (www.ippr.org)