Science & Research  What Your Baby's Gender Could Say About Your
Genes  Male lion with cubs in Gol Kopjes, Serengeti National
Park, Tanzania  Photograph by Joe McDonald/Corbis   There is a
term—my in-laws introduced me to it—for children born into a
life of inherited wealth and unearned leisure. They are
“fortunate sperm.” A newly published study gives that term new
meaning. We all assume that the gender of a child is basically
random—the result of a ferocious, wriggly race between tens of
millions of sperm to get to and burrow into the waiting egg. But
the new research suggests that mothers in a wide and diverse
array of mammal species are able, perhaps unconsciously, to
choose the gender of their offspring. Somehow the moms are
rigging the game.  The idea that this might be the case was most
famously laid out in a 1973 paper (PDF) by the evolutionary
biologist Robert Trivers and the computer scientist Dan Willard.
The central insight was that gender has a lot to do with one’s
reproductive success. In many m