“The informant wears a yellow string tied around her wrist. It was given by her mom for luck.”
After thoughts: The strings are called blessing cords and used in Buddhism practice. In the traditional practice, the Lama ties a knot in the cord and blows a mantra into it which makes a blessing. This allows you to take your teacher with you wherever you go. This is similar to many other religious traditions where the teacher is associated with spiritual blessings. They are meant to touch your body and purify any negative mantras.