For Jennifer Lopez and Marc Anthony, joyfully nesting with their month-old twins means diaper duty, sleepless nights and the best sung lullabies in the business, PEOPLE reports in its latest cover story, on sale Friday.

The pair were interviewed at their Long Island estate, where they have been holed up since Lopez gave birth by C-section on Feb. 22 to Maximilian David and Emme Maribel. Since then, Lopez, 38, has shed most of the nearly 50 lbs. she gained during pregnancy – and has also entirely re-adjusted her attention.

“I’ve been very career-oriented my whole life and very focused on my own world and my own life, and all of a sudden the focus just shifts. It’s like, ‘Whoosh!’ I want to do everything for them,” says the new mom.

For Anthony, 39, life has changed, too. “I don’t go to sleep!” he admits.

Describing the arrival of the babies, Lopez says, “To me, they both looked like Marc. I think that’s the first thing I said: ‘She looks like you! He looks like you, too!’ My doctor said, ‘Did Jennifer get a gene in here or what?’ ”

For more on this story, including details of how the couple learned Lopez was pregnant, and more photos of the twins, pick up this week’s PEOPLE, on newsstands Friday