The tradition started in 1993, when Agents of S.H.I.E.L.D. actress Ming-Na Wen and her husband, Eric, celebrated their first Christmas together. "We were young and in love, and we picked an ornament with two cats snuggling," she says. "We thought it was very cute." Since then they've added one ornament a year to their collection - although they started doubling up once their kids Michaela, 13, and Cooper, 8, wanted to choose their own. "Each ornament has a story," Wen says. "The kids love having them from when they were born or from vacations that we've taken together." Once the tree - handpicked by Michaela and Cooper - is brought back to their Calabasas, Calif., home, the decorating party begins. The family reminisces as the ornaments are unwrapped, each one "sparking memories." While it's a full-on family affair, Wen admits to a little late-night mommy tinkering. "I rearrange it after the kids go to bed," she says. "It gets a little bottom-heavy."