Thrice blessed

摘要

Throughout history, twins have provoked mixed feelings. Sometimes they were seen as a curse-an unwanted burden on a family's resources. Sometimes they were viewed as a blessing, or even as a sign of their father's superior virility. But if Shannen Robson and Ken Smith, of the University of Utah, are right, twins have more to do with their mother's sturdy constitution than their father's sexual power.rnAt first blush, this sounds an odd idea. After all, bearing and raising twins is taxing, both for the mother and for the children.