Very true Jinxremoving. My husbands entire family can eat anything, and do, and never gain weight. They are also all over 6' tall. I am 5'5" and when standing next to any of them look like a basset hound next to great danes!
One of my very dear friends has always been very thin, and was called beanpole growing up. It wasn't until she turned 60, that her metabolism started to slow, and now she is "careful" about how much she eats.
I suppose both ends of the weight spectrum can be frustrating, me being at the hard to lose, you on the hard to gain.
I guess as long as we are all healthy, which is what's really important, the rest is just aesthetics.
Perhaps eating lots of carbs, such as pasta would help put some weight on. I know I have to limit myself to very little of these foods to even lose a pound.