Sexual mores: Love in a cold climate A FEW years ago Susan Quilliam, a psychologist, started updating "The Joy of Sex," a seminal 1970s guidebook to pleasure. Talking to Britons about their sex lives, she found a curious mixture of hedonism and puritanism. People had apparently become more experimental in their own sex lives. But their attitudes to infidelity were strikingly prudish. A large survey published on November 26th confirms her hunch. The National Survey of Sexual Attitudes and Lifestyles (Natsal) reveals a more liberal society, increasingly tolerant of sexual diversity. Growing numbers of women have had some kind of homosexual experience: 16% of 16- to 44-year-olds, up from 10% in 2000. But permissiveness is out. Between the first and second Natsal surveys, in 1990 and 2000, the proportion of men aged 16 to 44 who condoned casual trysts rose from 20% to 27%. In the most recent report, the proportion fell back again, to 20%. And Britons increasingly frown on affairs. In 1990, 45% of men said any non-exclusivity in marriage was wrong. Now 63% condemn it. Women take an even dimmer view. The proportion deploring affairs has risen from 53% to 70%. Catherine Hakim, a sociologist, reckons that the financial crisis could be partly to blame. In hard economic times, people cling to whatever they have got, including partners, and sexual adventure becomes less acceptable. Ms Quilliam adds that the young have seen the destruction that infidelity wreaked among their parents and grandparents - the first really free to dabble in casual sex. That fits with Natsal's survey, which suggests the young are most hostile to adultery. They are conservative in other ways, too, boozing less and taking fewer drugs than their predecessors. Teenage pregnancy has not been so rare since 1969. Rates of sexually transmitted infections are rising among every age group except those under the age of 24. The sharpest fall is among teenagers. As attitudes shift, sheets go unruffled. In the latest survey men, both single and attached, said that on average they had had sex 4.9 times in the previous four weeks, down from 6.2 occasions in 2000. For women the tally fell from 6.3 to 4.8. The recession may be to blame for that too. Unemployed people tend to have less sex. Those who have kept hold of their jobs are too worried about hanging on to them to have much time or energy for fleshy frolics.