Motherhood seems like a natural fit for newbie Rebecca Romijn. The wife of Jerry O'Connell is featured on the cover of the latest issue of InStyle and posed for an inside spread with their darling duo — 5-month old twin daughters, Dolly Rebecca Rose and Charlie Tamara Tulip. And, it seems that though the celebmama ate for three during pregnancy, the postpartum pounds have been anything but stubborn. Rebecca said:

I'm a jeans size up from where I usually am, but there's nothing about it that freaks me out—I've always said that sexy is having a really strong sense of yourself and never taking yourself too seriously.

After debuting a svelte figure just weeks after leaving the hospital with her new babes, the actress has attributed her rapid weight loss of about 60 pounds in four months and fit physique to two things — breastfeeding and Spanx, not exercise. To see what she said,

. Last month, Rebecca told People:

I think within the first three weeks, I took off like 35 lbs. without doing anything! I haven't been able to work out that much because I have twins. It's impossible to get back into a regular schedule.

It looks like the former model turned mama has some amazing genetics.