I remember being equal parts curious and disturbed several years ago when my mother told me that she really enjoyed “The 40-year old Virgin.” Disturbed, since one naively doesn’t like to imagine one’s mother enjoying such sexually explicit humor (much in the same way we don’t like to think of our parents actually having sex) ,and curious since she really enjoyed Steve Carrell’s portrayal of the lovelorn titular character hidden amongst writer/director Judd Apatow’s bawdy buddy repartee.

Apatow’s latest, “Knocked Up,” is more of the same, but this time he has created a chick flick wrapped in deliciously crass clothing. Think “She’s Having a Baby” meets “American Pie.”

Up-and-coming E! News anchor woman Alison Scott (Grey’s Anatomy’s Katherine Heigl) hooks up with pot-smoking slacker Ben Stone (writer Seth Rogen) only to find that their one-night stand results in more than sheepish grins in the morning. Alison decides to keep the baby and Ben says that he’s “on board.”

But, even as Alison and Ben try to make their relationship work, Alison’s sister’s (Debbie troubled marriage seems to serve as a preview–and Ben keeps disappointing Alison (saving his bong during an earthquake instead of her). Needless to say, in the end, Ben rises to the occasion, getting a real job and his own place; things end up happily for the fledgling family.

The movie is at turns deeply touching, hysterically funny and doggedly realistic, especially the portrayal of Pete’s (Paul Rudd) and Debbie’s (Leslie Mann) marital problems–suspicions of infidelity, fears of not being able to be loved. As Pete says, “marriage is like ‘Everybody Loves Raymond,’ except that it’s not funny.”

Heck, even the fact that Heigl’s Scott would hook up with a schlub like Rogen’s Ben actually comes off realistic. But, I have to agree with Slate’s Dana Stevens that the least realistic aspect of the film is the fact that abortion was never really discussed as an option, but alluded to in silly ways, as in one scene where one character suggests something “that rhymes with sma-smortion.”

“It’s just not believable that, in Alison and Ben’s upper-middle-class, secular L.A. milieu, abortion would not be matter-of-factly discussed as a possibility in the case of a pregnancy this accidental,” writes Stevens. “If she doesn’t want one, great–obviously, there’d be no movie if she did–but let’s hear about why not. Otherwise, her character becomes a cipher, a foil for Ben’s epiphanies about growing up, without being allowed any epiphanies of her own. The biggest unanswered question about Heigl’s character is one the movie never tiptoes near–why does she decide to keep the baby?”

In an interview with The Onion’s A/V Club, Rogen notes that the choice wasn’t in any way political: “We always knew that was not something we wanted to dwell on. It wasn’t a movie about a woman deciding whether she should keep her baby; it was about a woman who decided she was going to keep the baby. … But it just seemed like, you need her to make that decision to get to the other hour and a half of the movie, so let’s just try to get there.”

As much as I would like to think that Alison’s decision to keep the baby is merely a device to motivate this charming story about two unlikely people finding each other, it seems too glib and naïve for a movie that illustrates so smartly and honestly life’s most serious moments with such amusing aplomb.

Personal political leanings aside, “Knocked Up” is neither conservative, nor liberal, but another Apatow fairy tale–foul-mouthed and full of feeling. A mix that even a mother could love.