When Shreyas Deokule phoned his parents in Mumbai, India, in the summer of 2008, he received unexpected news. They had posted his profile on a matrimonial Web site.

"We had a major argument after that," said Deokule, 30, who works as a software consultant in Kansas City, Mo.

Eventually, Deokule said, his parents managed to persuade him to leave the profile up on the matrimonial Web site. They promised that his sister would deal with all...