People magazine did not Photoshop the picture on its latest cover of Brad Pitt and Angelina Jolie's smiling newborn daughter Vivienne, as New York magazine suggested in a recent piece, a rep for the celeb weekly told FOXNews.com on Thursday.

“Contrary to blog speculation, PEOPLE did not photo-shop Vivienne Marcheline Jolie-Pitt’s smile. One can only guess that she is smiling because her parents are Angelina Jolie and Brad Pitt," Sandi Shurgin Werfel, People's director of public relations, told FOXNews.com.

In the image, 3-week-old Vivienne Marcheline, one of the couple's two newborn twins, appears to be smiling or laughing as she lies next to brother Knox Leon in her mother's arms.

Click here to see the cover from People

But New York magazine cites an article from Parenting magazine that says babies don't smile from exterior stimulation until 2 to 4 months of age.

Click here for the Parenting article

New York magazine suggests the picture was Photoshopped or "the babies could have been born earlier than reported to avoid paparazzi attention, as has been rumored. Or Angelina and Brad, predicting their future acting careers, are already lying about the infants' ages."

However, the same Parenting article also says babies have been seen in the womb via ultrasound smiling in the last trimester. This is believed to be a natural response to the internal pleasure of falling asleep or waking up.

Click here to read more from New York magazine.