Reminds me of the old "old dog, new tricks" phrase. People who have lived for half a century or more being told that something is a certain way, can't get their mind around it.
My dad is a classic example. He has wanted to lose weight for about 10 years now, and has had limited success. He's not THAT overweight, only about 20lbs or so. But he's not willing to try new things, and sticks to what he knows.... which is that fruit and starches and lots of them, are healthy for you.... as well as veges and some meat etc. Which is true, it is healthy. But he doesn't like the idea of cutting carbs somewhat.... and tells me that's not a healthy way to do things.
Well, while I'm there getting more than enough fibre and losing 25lbs of fat in 10 weeks, he doesn't change an inch.
It's difficult to introduce people to something which goes against everything they've known. Namely fat makes you fat, and carbs are good for losing weight.