What does a white, middle-aged drill instructor have in common with a black teen whose mom is dead and has been in and out of foster homes? something they’ve been exposed to at the camp? Toothpaste, deodorant, food, sexual history?

And the winner is: ticks. Gotta be Lyme disease. So the first round of doxycycline is on the house.

Trouble is, Sarge isn’t responding to treatment, which rules out Lyme disease. Arsenic is ruled out (3M might have well stayed home!), but botulism fits the bill. Landon could have contracted it when he cut himself, and Sarge might have abrasions somewhere on his body.

Wrong again. almost the top of the hour. the light bulb this week goes off while House is treating a clinic patient for abrasions.

It occurs to House that Landon has had a shot of Lidocaine to numb him so he could get his head stitched up. Sarge had antihistamines. those drugs can be a genetic trigger for porphyria.

Genetic, you ask? Turns out the key to this mystery is “Star Wars.” Cue the heavy breathing apparatus: Yes, Landon, Sarge is your father.

First round of Hematin is on House. we leave father and son resting uncomfortably.

The “B” story involves Chase’s social networking site being maliciously hacked, which has to do with a threesome he had after a wedding.

The “C” story has to do with House trying to train Rachel in simple tasks in order to gain admission to a prestigious preschool. Sit. Play. Eat the treat. Who’s a good girl?

(Speaking of good girls, Olivia Wilde is still in the opening credits. It’d be nice if between “Tron: Legacy” and  “Coyboys & Aliens” she could drop by.)

– Linda Whitmore 

Photo: an ailing drill instructor (Sasha Roiz) keeps a deadly secret from House (Hugh Laurie). Photo: Harper Smith / Fox.