I heard something simmilar to that also.
It's said to be because of the high amount of calcium in milk, but I personally LOVE milk and know that calcium is a lot better for ones's overall health than people thought years ago.
It's known to be more than just good for your bones and teeth now.
The problem with calcium is that it's one of the hardest minerals for your body to absorb, but consuming vitimin D (also in milk and absorbed through your skin from the sun) with calcium helps with calcium absorbsion, and I'm pretty sure magnesium also helps.
Cafine has been said to block the absorbsion of calcium when they're consumed too close together.
I honestly don't think that a half gallon a day will cause the kidney stones, but it all depends on the person. My uncle and sister both had them and according to them it was terrible.
If it runs in people's families then I think I would have had them by now because I used to drink a half gallon of milk a day and now I don't keep track anymore but still drink a lot. My vit and min supplements also have 17% USRDA of calcium per pill and I take three per day.
Anyway, I hope this helped.
You can also check WebMD.com and search for kidney stones if you still have questions.
There are a couple of different kinds of kidney stones. I've had 2 and believe me, you dont ever want to get one. I had to get operated on to get the first one out (they just broke it up so couldnt tell me what kind it was) and it was the worse thing Ive ever gone through. The first one I got was when I was on a huge protein kick, I was eating a ton of chicken breasts, tuna plus protein shakes a day. The second one was when I had converted to a vegetarian so I cant draw any conclusions as to what was the cause. The most important thing is water though, a ton of it. Also if you feel one coming on drink some pure cranberry juice (not the cranberry cocktail type stuff)
It'll feel like you got stabbed in the side on your lower back if you have one.
"People who form calcium stones used to be told to avoid dairy products and other foods with high calcium content. But recent studies have shown that foods high in calcium, including dairy foods, help prevent calcium stones. Taking calcium in pill form, however, may increase the risk of developing stones."