The best way to break your kittens of this bad habit is to discourage them. ... Over time, your kittens will get the message that suckling on your skin is not an acceptable kitten behavior. It will take some time to break this habit, but you will be much more comfortable when you do. And they will love you just as much!
Should I nurse my kitten?
For the first month of life, kittens require very little care from the owner because their mother will feed and care for them. ... The kittens need to be kept warm and to nurse frequently; you should check them every few hours to make certain that they are warm and well fed.