Did you noticed that? Here is my "philosophical" interpretation of this magnificent cartoon.
Peter is "Carefree", loves to have fun in the pub, outlandish business with friends, not thinking of anything problematic, good food and resting on the couch watching TV.But he's also "Authority",at the end all revolves around what he does. And when it comes to family and friends, is more than ready to lend a hand, sometimes with incredible steadfastness and affection.
Lois is "Responsibility",is a more attentive parent than Peter, strives to understand the children even when the views are divergent. In addition, it is often her giving inputs to Peter in the decisive moments for their family.But she's also "Pleasure," she cheated on Peter on several occasions, made use of Spinelli and more generally, is aware of her beauty and full of complacency in being courted and coveted as one of the most attractive women in Quahog.
Meg is "Repulsion", no one seems to really appreciate her, is considered wrongly ugly and insignificant, and often people fail to capture the sweetness inside of her. This makes Meg often gray and sad, and this only increases this sense of...

Family Guy Script
Episode: ###
Stewie Quagmire
Summary: When Stewie gets a cold, Lois is forced to take him to the doctor, where his birth certificate shows up, revealing that he’s Quagmire’s son.

Key: ( ) = location
{ } = info
[ ] = Action
/ \ = commercial break
(Griffin house)
(Living Room)

[Family sitting on couch watching TV]

Dianne Simpsons: In local news the, a cold academic has swept through Quahog.
Tom Tucker: Well, Dianne I’m not sure if it’s an academic. It’s just a cold.
Dianne: Do you really have to contradict everything I say?
Tom: I’m just saying, it happens once a year, it’s not exactly an academic.
[Dianne narrows eyes] Dianne: Now onto Ollie Williams, who’s on the front line to deliver the story.
Tom: What’s it like out there, Ollie?
[Dianne narrows eyes again]

[Cuts to middle of city. Shows Ollie in a gas protection suit.]

Peter: What the hell is he talking about?
Englishman: Oh, it’s Cricket. Marvelous game, really. You see, the bowler hurls the ball toward the batter who tries to play away a fine leg. He endeavors to score by dashing between the creases, provided the wicket keeper hasn’t whipped his bails off, of course.
Peter: Anybody get that?
Cleveland: The only British idiom I know is that “fag” means “cigarette.”
Peter: Well, someone tell this “cigarette” to shut up.
-Family Guy
Tonight there’s a new reality show on Fox: “Fast Animals, Slow Children.”
-Peter Griffin
When I stick this army guy with the sharp bayonette up my nose, it tickles my brain. Hah hah hah...ow. Oh, now I don’t know math.
-Chris Griffin, Family Guy, “The Kiss Seen ’Round the World”
Meg: Excuse me, Mayor West?
Adam West: How do you know my language?
-Family Guy, “The Story on Page 1”

Police blotter: We have a gang shooting on 3rd and Main. Three wounded, one dead.