So how has she managed a supermodel body after baby?
"I have three children," she tells PEOPLE. "That keeps you busy all the time. I work and we do a lot of things that are active. We work in the garden. We jump on the trampoline. I just started playing tennis with my husband. We climb in the tree house with the children. We go to the park and feed the ducks. We are always mobile."
But the 34-year-old German native acknowledges that kids and ducks only go so far – she cops to other help to pull off her provocative look in the black-and-white print ads in which she poses topless (with strategically placed blond locks to keep things PG-13.)
"There were 20, 30 people on set to take the pictures," she said of the photo shoots with Brett Ratner, normally an action movie director moonlighting as a fashion photographer. "He had a lot of assistants. So I don't have to do that much. They all make me look good."
"He always does a butt check," says Klum, who returns the favor. "I like him in jeans. I like him in anything. I like him without anything."
Which almost makes it obvious how they keep their relationship hot.
Says Seal: "It keeps itself hot."
Reporting by KC Baker