I have this, too, and I seem to have the opposite body characteristics of many. I have a very long waist, and I tend to be broad and square across the shoulders. I am not sure it has anything to do with a "forward neck" since when I stand with proper posture the problem gets worse, not better. I think perhaps it means that most bodies are not straight and square across the back and that they taper in the back, too, although to a lesser degree than in the front. Perhaps the lack of back neckline darts is the issue. It sounds like more people might need them than not.

Such an interesting thread! Diana, I'm like you in the front: wider rib cage (what I call singer's rib cage - lol) and a wider sternum. I have some of the same bra fit issues, too, but I'm as broad across the back as I am in the front. I have to size up in sheaths, but they generally work, even if they don't quite flatter. I have a slightly long waist, and at only 5'6, I need more length overall. I find that talls, when I can find them, actually fit well and I like the close-to-midi length!

P.S. I adored the Vera Wang on you!