Which Americans have the most sex partners? General Social Survey participants were asked how many different partners they had in the past year. I calculated the mean for 18-30 year olds from ethnic groups with at least 100 respondents:
Mean sex partner in last 12 months (women in parentheses, then the sex difference):
Blacks 2.39 (1.44) +.95
Irish 1.92 (1.36) +.56
Italians 1.85 (1.19) +.66
American Indians 1.83 (1.38) +.45
Mexicans 1.73 (1.48) +.25
USA 1.74 (1.32) +.42
Germans 1.53 (1.21) +.32
English/Welsh 1.51 (1.28) +.23
Blacks have been characterized as the most sexual race, but according to GSS data, this is more true of black men. Mexican American women report more partners than do their black counterparts. Other surveys portray black women as being somewhat conservative about sex. And while other studies also suggest that blacks have more partners, they often do not find that blacks have sex more often, or that they engage in more novel kinds of sex (e.g., anal). In a well-respected study described in the Social Organization of Sexuality, Hispanics had the most sex, and were the most experimental.
The women's rankings tend to follow the men's: the number of partners a woman has are, in part, due to the kind of men she is dealing with. If she is sleeping with someone, she probably wants to keep him, and if she is sleeping with multiple guys in a year, the guys are not sticking around. There is also a pattern of more gender-traditional groups having the biggest sex differences (Italian guys can sleep around, but not the girls).
As we have seen with many kinds of behavior that grandma wouldn't like, rates are highest among non-whites, or among whites from Catholic or southern European countries. (Drinking is an important exception). You and I might not think any group is ultimately superior to another, but Grandma is starting to think that whites from traditionally Protestant countries (and perhaps East Asians and Jews if I studied them more) are.