By Stephen T. Asma

"But Dad, that's not fair! Why does Keaton get to kill zombies, and I can't?"
"Well, because you're too young to kill zombies. Your cousin Keaton is older than you, so that's why he can do it. You'll get nightmares."
"That's sooo not fair!"
"Next year, after your birthday, I'll let you kill zombies."
It's not exactly Little House on the Prairie,but this is a real conversation between my 8-year-old son and me. Age-ratings on zombie-killing video games are just one of modern life's great injustices, according to my son.