Why girls want to be boys

The mechanisms by which sex is genetically determined are bewilderingly div erse and appear to change rapidly during evolution.((1)) What makes the sex -determining process so prone to perturbations? Two recent articles((2,3)) explore theoretically the role of genetic conflict in sex determination evo lution. Both studies use the idea that selection on sex-determining genes m ay act differently in parents and in offspring and they suggest that the re sulting conflict can drive changes in sex-determining mechanisms. (C) 2001 John Wiley & Sons, Inc.