15.

For 15, here's an Ask the Experts letter from Teenwire.com and written by a 15-year-old:

Dear Experts,

I'm 15 years old I want to have a baby am I too young? All i've ever wanted to do ever since I wuz a kid is to have a baby i'm finally able too and I want one realy bad is there sometin I can buy to predict when I ovalite or is there sumthin I can do to let myself know when I am going to ovalite????

paigy34, 12.28.04

This kind of reminds us of that Go Ask Alice book, supposedly written by an anonymous teenager who kept a diary of her fatal drug use but that was really written by one Beatrice Sparks, author of such other "anonymous" books as Almost Lost: The True Story of an Anonymous Teenager's Life on the Streets and Annie's Baby: the Diary of Anonymous, a Pregnant Teenager. We think this mainly because, while we do know that the average 15-year-old can't spell or read, the word "ovalite," in our mind closer to "Ovaltine" than "ovulate," just doesn't ring true. And "wuz" is so 1995, not 2005.

Incidentally, Teenwire does answer this 15-year-old's question with some long, bullet-pointed diatribe, which is fine for someone who can read. We have a simpler answer: of course you should have a baby at 15. Obviously your mother doesn't love you, and your father took the Escalade and ran or is dead. You need to fill that void with a baby. Duh. A baby is harder to kill than a plant and doesn't have to go outside to use the bathroom, like a dog. It's clearly the easiest living thing you can acquire that will love you unconditionally.