Milk has calcium which is required to strengthen and allow for the development and growth of your bones. Thus you would get taller by having a sufficient amount of calcium for your bones to use. Milk can cause you to gain weight if you drink too much of it, I would recommend having skim milk and having it in moderation (1-2 cups per day). If you combine this with a healthy diet, workout, and meal plan you shouldn't be gaining much if any weight because of it. Just make sure you get good excercise and eat the right kinds of foods and your weight should be fine.