IStock Photo 10610676 © Emre Ogan

Sex: If you ask certain members of certain administrations, they’ll say nobody should do it. If you ask people whose ages end in -teen, they’ll say practically everybody’s doing it.

Faced with these extremes, it’s hard to tell who’s doing it. “It” being, in this case, premarital sex—engaging in intercourse before marriage or without ever marrying. The subject of countless after-school specials, the target of abstinence campaigns, anathema to chastity pledges and born-again virgins, premarital sex is a hot topic. But how common is it?

The answer is: in America, it’s almost universal. According to a 2007 study by the Guttmacher Institute in New York, 75% of people have had premarital sex by age 20 (77% have had any kind of sex). By age 44, rates climb to 95%.

Why are the numbers so high? One reason may be that the average age at which people get married has gone up three years in the past quarter century, from 22.1 to 25.8 years for women and from 24.4 to 27.4 for men. Plus, a higher proportion of the population—from 16% in 1970 to 25% in 2004—isn’t getting married at all; a 2008 US Census Bureau report found that 30% of people over the age of 15 have never married, while another 19.4% are widowed, divorced, separated, or out of touch with their spouses or partners. Also, the average length of time between the onset of puberty (about age 12 and-a-half for girls and 14 for boys) and first marriage has now reached 13 years, eons to sexually-able bodies and brains.

The way Americans view premarital sex has changed dramatically over the past several decades. A 2004 survey found that only 1 in 3.33 of people born before 1940 believe premarital sex is OK. The odds increase to 1 in 1.67 (60%) for those born between 1940 and 1954. 1 in 1.41 (71%) of people born between 1975 and 1986 approve of premarital sex.

Blame the sexual liberation of the ’60s, you might say (Many do). Surely your grandparents’ generation wasn’t slipping on condoms before wedding rings.

Or maybe they were. Premarital sex rates have remained fairly constant since 1960, and about 90% of women born as far back as the 1940s have done the dirty before tying the knot (if they’ve tied it at all). A headline from The Senior Journal based on the Guttmacher report put it plainly: “Almost all Americans Have Sex before Marriage and Have for Decades.”

Perhaps it’s social mores and public perception that have changed while human nature remains the same.