A/n: Did you ever wonder how a smart cookie like Lisa could have been sired by such a nincompoop as Homer? Well, maybe she wasn't! I realize this issue was addressed briefly in the Season 7 episode "Mother Simpson" and even more in the Season 9 "Lisa, the Simpson", but hey, who said Simpsons plots relied on continuity?

Chapter 1- A Family Secret

"Owwwwww!" Homer yelled as he jumped away from his workbench where he just mashed his thumb with a hammer. Then, stumbling over a pile of scrap lumber with a mild expletive, ran up the cellar stairs to be placated by Marge. Hopping from one foot to the other like a kid playing hopscotch, Homer watched Marge bandage the purple, swollen finger.

"Maybe we'd better go to the hospital emergency room. We want to make sure you didn't break the bone."

"D'oh, what a way to spend Saturday," Homer lamented.

Marge loads the family in the car and heads for the hospital. Of course, they are greeted by the ever jovial Dr. Hibbert.

Marge begins, "I'd like Homer thumb x-rayed to make sure it isn't broken, doctor."

"He, he, he." chuckles the doctor. "Well maybe it's not. Let's just see here…." And gives a good squeeze to Homer's sore thumb. Homer stares blankly for a few seconds then winces.

"Hmmmmm. Maybe we SHOULD x-ray that thumb, Mrs. Simpson." concludes Hibbert.

Maggie has dozed off in Marge's lap, but Bart and Lisa are totally bored and start getting fidgety. Marge notices their unease and fishes around in her purse. Producing two five dollar bills, she hands one to each child. "Why don't you go the hospital cafeteria and get some lunch. It looks like we may be here a while. Come back here when you're done."

The kids toddle away and start looking for the lunchroom, but unfamiliar with the hospital layout, are soon lost in a confusing labyrinth of corridors. White jacketed men with black bags and women in white dresses with clipboards hurry to-and-fro paying little attention to the strayed children who can't get anyone's attention to ask for directions. Bart and Lisa continue exploring the hallways. They finally wander into a deserted looking area. Bart spots a sign on a door "RECORDS".

"Ho, ho," he chuckles. "Over here Lise – look." Pointing to the door.

"No, Bart, don't." cautions Lisa as Bart starts to push against it. It creaks open a crack.

"Somebody messed up not locking THIS door. Hey, maybe we can get the dope on some bigshot, than blackmail him to keep quiet about his condition." fantasizes Bart. (Imagining Mr. Burns throwing handfuls of money at them, Bart chuckles again).

"I still don't like this, Bart. This place gives me the creeps." shudders Lisa.

As the door opens wider a slit of light illuminates a small area on the wall where numerous files gather dust. The section they see first is labeled "Maternity" and there is just enough light to see a name on one of the folders – "Simpson."

"Cool!" exclaims Bart reaching for the folder.

"I think we should just leave right now." Lisa says while trying to grab Bart's shoulder and guide him away from his obviously intended mischief. But while doing this, she accidentally knocks the folder out of her brother's hand. Of course it lands conveniently on a small desk and opens to reveal a file on Marge Simpson. Both children are riveted now as they begin to scan the information. Lisa reads aloud:

"Marge Simpson has registered with the fertility clinic due to her husband's apparent sterility."

"Dad….sterile?" queries Bart. "I find that hard to believe. He always smelled kinda bad to me!"

"Not that kind of sterile, dolt!" exclaims Lisa. She continues, tracing the words on the page with her finger as Bart follows with his eyes. "Mrs. Simpson is scheduled to be artificially inseminated on ……..this is date almost nine years ago. I fact it was nine months before I was……." She trails off lost in thought.

"What does arfitical insmenimation mean, Lise?" asks Bart.

Lisa whispers in Bart's ear. Bart screams. Lisa tries to quiet him, but continues reading:

"The donor will be……." Lisa's screams join that of Bart's.

(to be continued)