Chrissy Teigen‘s mom, Vilailuck Teigen—known affectionately as “Yāy” to Teigen’s online fans—is officially a U.S. citizen. Teigen took to Twitter on Tuesday evening to share a video of her mom, who’s originally from Thailand, reciting the Pledge of Allegiance. In the clip, Vilailuck can be seen holding her two-year-old granddaughter, Luna, who’s waving an American…