Rebecca Romijn, Ricky Martin, Nancy Grace, Holly Hunter, Dennis Quaid, Angelina Jolie, Jennifer Lopez, Patrick Dempsey, Marcia Cross, Sean Combs, Lisa Marie Presley, and Julia Roberts are all riding the latest Hollywood trend, and it has nothing to do with apparel, beachside homes or religions. Instead, each of these stars has been inaugurated into the enviable POT group—otherwise known as Parents of Twins.

There's something undeniably novel about the arrival of two babies at once. It's double the joy for the trouble. (Although many a parent would quip, "You also get double the trouble, too!") And I imagine there must be an inherent sense of pride. After all, what most do with one, they did with two.

When I look around, I count only a very, very few family members, friends and even friends-of-friends who've likewise been blessed with "more bang for the buck" kid-wise. The average rate of giving birth to twins in the United States is only some 31 births per 1,000 women (according to birth statistics from Rush University Medical Center). So are the stars averaging more twin births than the general public? While I've always been a bit math-challenged, it looks like they may indeed be blessed with great looks, fat bank accounts and incredible fertility. Talk about a trifecta!

The reasons behind the high numbers are complicated. Some of these moms have waited a bit longer to begin their brood, and while older women are statistically less fertile, they do have a higher rate for non-identical twins. Umm...huh?! This makes my head swim a bit. But it all may be due to an increase in the follicle-stimulating hormone, or FSH hormone. The older you are, the fewer and lower quality of eggs. To compensate, your body starts churning the FSH, which can cause the release of more than one egg during ovulation. I've read that something like 17 percent of women over 45 have a chance of conceiving twins, so age is Possible Reason No. 1 for the twin-mania hitting the celeb sect.

Possible Reason No. 2 is trickier, especially because no one is really talking about it. Fertility treatments, which can be exhausting and incredibly expensive, are not something you read a lot about on star-watch Web sites and magazines. And there's been little outright talk that fertility treatments may be behind some of the latest doubled bundles of joy. (Plenty of private musing on blogs and in less-than-reputable magazines, for sure, but still nothing definitive. So why won't any celebrity admit to having some help in this area? Certainly parents who struggle with infertility would welcome a famous face to bring attention to what is an all-too-common plight. But I'm sure many celebrities would prefer to keep their private matters, well, private.) Still, given that some of our most beloved icons are a little older and can most definitely afford the costly and time-consuming treatments, it makes perfect sense.

Granted, there are a bevy of other possible reasons, but a high-powered photo lens can only get me so far. I'm not sure if any of these blessed moms have twins running in the family, as genetics play a big role. Wait! Internet, you so rarely let me down. Julia Roberts made it clear to one celeb mag that twins ran in her family. As did J-Lo. Jerry O'Connell has been quoted as saying twins are found throughout his Irish heritage ... but I hate to break it to him that my research shows only the mother's family history impacts this decision-making process.

Another thought: Do they eat a lot of dairy? A recent study by Dr. Gary Steinman of the Long Island Jewish Medical Center in New Hyde Park, N.Y., found that women who eat dairy are five times more likely to conceive twins than those who don't. Dr. Steinman theorizes that synthetic growth hormones found in milk may be the culprit. But since most dairy isn't exactly low in fat, it seems unlikely it makes up a good portion of diet-conscious meals. I can't exactly envision Rebecca Romijn going crazy in the cheese aisle. Me, on the other hand? That's another story.

A final theory is that if you're taller or overweight, your odds of having twins increase. This hypothesis fails outright for most famous moms. I mean have you seen Angelina Jolie? She didn't even look overweight when she was about to burst with Vivienne and Knox. (How does she do that?! I was pregnant with ONE and was asked if I was carrying twins or triplets.)

Whatever the reasons behind the influx of twins, it has many a normal mom jealous. Inquiries at preconception sites abound with women wondering how they, too, can be doubly blessed. So is Hollywood feeding this desire or simply reflecting it? It's hard to say, but given the numbers, twins aren't necessarily easy to come by ... or birth, or feed or change -- all simultaneously. It's enough to make this mom get sweaty and nervous at the mere prospect. But I've no doubt these Hollywood twins will be well taken care of and that their mommas will make the process look chic and effortless. And I'll gladly watch as these beautiful bouncing babes appear here and there in paparazzi pics and ... all while keeping an eye out for new members of the POT coalition.