DNA Tribes is correct that siblings can and do have very diverse DNA. Your autosomal DNA is a random subset of your mother's and father's DNA (50% from each parent). Two siblings will not have the same results for the same reason that they do not look exactly the same. They do not get the exact same 50% from each parent. Even identical twins don't have exactly the same DNA (only almost exactly the same).
Calorie and Nutrition information for popular products from Steak n Shake: Per 1 shake - Calories: 380kcal | Fat: 12.00g | Carbs: 63.00g | Protein: 11.00g. Per 1 shake - Calories: 890kcal | Fat: 29.00g | Carbs: 140.00g | Protein: 25.00g. Per 1 shake - Calories: 700kcal | Fat: 23.00g | Carbs: 111.00g | Protein: 18.00g.
Depending on your calorie needs, a meal replacement shake should be about 300-500 calories, at maximum. The idea is that a meal replacement will yield a calorie deficit and help you to lose weight. Aim to keep your meal replacement shake to about 30-45 g of carbohydrate. You also want your meal replacement to have at least 3 g of fiber, which will help to keep you full and slow down the rate at which blood sugars rise.