January Jones has remained mum on the identity of her son’s father — and she intends to continue doing so.

“That’s my son’s business,” January told The New York Times of 1-year-old Xander‘s father. “It’s not the public’s business.”

And she says a Hollywood legend advised her to remain private.

“Jack Nicholson once told me: ‘You should never give your personal life away, otherwise people will pick you apart. They’ll never believe in your character,’ ” the Mad Men actress said.

“Women should have lots of secrets,” January added. “It’s our right to have secrets. Otherwise, what would we write in our memoirs?”

The blonde beauty went on to talk fashion. “Most of my choices are my ultramodern and very thought-out,” she said. But the red carpet, meanwhile, “I want to do things that are shocking,” she said.

In many respects she is still the small-town girl with Midwestern common sense.

“I wasn’t brought up with money,” she said. “I don’t think I’d spend more than $150 on a shirt.” She added: “I’m almost O.C.D.,” she said. “You will never find a piece of clothing on my floor. I can’t relax if I’m sitting in a mess.”

As for her sweet son, “His first word was ‘Mama,’ ” the proud mom said. “His second was ‘back,’ ‘cause I keeping saying, ‘Put it back.’ ”

In regards to consuming her placenta, she said, “It was like taking a vitamin blended into a smoothie. I’m a mammal. I nursed. I did all kinds of weird stuff.”