I received an email from a mom very worried that her of a 13 month old son does not like milk! Her two older children stopped bottles/formula cold turkey, but not her baby, he still loves his formula. She asked what should I do?
I think you have answered your own question as you said that you stopped formula and the bottle with your other two children cold turkey. You are providing him with healthy meals and if you stop the bottle and formula and ONLY give him milk in his cup he will eventually drink his milk.
Not only does he have good role models in his older siblings, if you don't cave and give him his formula or even juice or water he will drink his milk when he is thirsty. Not only does he no longer need formula after he is 1 year of age, he needs to get the majority of his calories from food rather than from formula. You also know that this is the easiest time to get rid of the bottle before he becomes attached to it.
He may be your strong willed third child (all children seem to have this title at some time) on this issue. I also agree with you that he needs to be a milk drinker and this is the time to establish get this set in stone. I have found that if you don't get children to start drinking milk at this age, then for the majority of children, they will not drink milk later on in their childhood and adolescent years. Although you can give him other dairy products to help him meet his calcium and vitamin D needs, it is hard to meet those daily requirements without drinking some milk.
So, I would just go with your previous habit and stop the formula and give it some time. He will drink his milk, he just has to get thirsty enough. This means that his siblings cannot give him other fluids either!