In a large bowl, combine the yogurt, garlic, olive oil, lemon juice, cumin, salt and pepper. Add the chicken, cover and refrigerate for at least 4 hours.
Preheat the oven to 350 degrees . Line 2 baking sheets with parchment paper. Thread twenty 6-inch skewers alternately with 3 chicken cubes and 3 grapes. Using a rolling pin, crush the chips in their bags. Transfer to a plate. Roll each skewer in the potato chips and place on the prepared baking sheets.
Bake the kebabs, switching the pans halfway, until the chicken is cooked through, 20 to 25 minutes. Serve warm or at room temperature.