Not so fast, say moms of girls, who point out that they have to contend with fussier fashion sense, more prickly social navigations, and a far greater capacity to hold a grudge. And as a daughter grows, a parent's concerns range from body image to math bias.

Stereotyping, or large kernels of truth? "I think parents use 'which is harder?' as an expression of whatever our frustration is at the moment," says family therapist Michael Gurian, author of Nurture the Nature. "Boys and girls are each harder in different ways."

Every child is an individual, of course. His or her innate personality helps shape how life unfolds. Environment (including us, the nurturers) plays a role, too: "There are differences in how we handle boys and girls right from birth," says David Stein, Ph.D., a professor of psychology at Virginia State University in Petersburg. "We tend to talk more softly to girls and throw boys in the air."

But it's also true that each gender's brain, and growth, unfolds at a different rate, influencing behavior. Leonard Sax, M.D., author of Boys Adrift, believes parents raise girls and boys differently because girls and boys are so different from birth -- their brains aren't wired the same way.

So, can we finally answer the great parenting debate over which sex is more challenging to raise? Much depends on what you're looking at, and when: