"The amazing thing is that the guys are always split 50-50. Age and income groups don't seem to matter," said Lisa Hayward, a UW doctoral student in biology and lead author of a paper reporting the findings in the current issue of the journal Evolution and Human Behavior.
The survey showed just 32 percent of women favor such routine testing. The difference in response between genders remained consistent in spite of marital and income status.
Previous studies have shown that generally less that 1 percent of married women bear children fathered by men other than their husbands. The exceptions are studies conducted among women living in extreme poverty in the United States, Mexico and England, where the rate was as high as 10 percent.
Researchers have speculated about why a woman would seek a father for her child other than her husband and often conclude that it is to improve the child's genetic heritage or to gain parental investment from more than one male. Either way, it would normally be advantageous for the woman to keep the child's paternity a secret so that her husband would continue to care for the child as if he were the father.
"There's this fascinating aspect that when we ask the guys who do not favor paternity testing why they are opposed, more than half of them say, 'Ignorance is bliss,'" said co-author Sievert Rohwer, a UW biology professor. "Then the question becomes, 'Whose ignorance, the cuckolder or the person being cuckolded?'"
Rohwer said the researchers speculate that few men are likely to father offspring with women to whom they are not married.