I know the above data comes from Australia, but a buddy of mine works for a health insurance company. We had a conversation about this a few years ago. A lot of women get their child's DNA tested for genetic disease analysis. He says that around 20% -- think about this, guys -- 20% of the children who are tested are NOT the offspring of both claimed parents. That's one kid in five. This is in America.
I would have called bull**** but I remember when I was a kid in the 70's a whole firestorm over blood type genetics being "wrong." There was a national sampling of blood types to determine how blood types are being handed down. About 20% of the kids tested did not have the "right" blood type.
Along comes genetic testing, the test is repeated, and genetic incompatibilities show up. . . in about 23% of the kids. This was in the 90's. I remember reading the article in college and discussing it with my buddies.
2.7 kids per married couple in the USA. Nearly 1 in 4 kids misattributed to their father. That's every other woman in this country, by my math, that's not only having affairs, but getting corked up. By the time you figure in birth control, pregnancy rates, etc? I'd believe 7 in 10 women in America cheat. Hell, I'd believe 8 in 10.
http://www.britam.org/DNA/BAMAD52.html#Non
"Actual figures range from 1 percent in high-status areas of the United States and Switzerland, to 5 to 6 percent for moderate-status males in the United States and Great Britain, to 10 to 30 percent for lower-status males in the United States, Great Britain and France. Moreover, the men most likely to sexually hoodwink the lower-status males are men of higher status."
This is about pregancy, mind you. Birth control availability and rates are considerably higher for "higher-status females" in the U.S.
You bet your @** they cheat. For me, this was like discovering the great buffalo herds. Go get some.