From my less than scientific observations (past heavy experience with bodybuilding/weightlifting), at similar levels of leanness 15%, 1 inch = 5 lbs. A well known calculator kind of confirms that[0]. I could see less lean individuals being 10 lbs or greater at one inch but 26 sure does seem high.

[0] - http://www.weightrainer.net/bodypred.html

For instance, if you put in the values 69 inches tall, 7 inch wrists, 9 inch ankles and 15% BF (not super lean but not overweight), you get a maximum lean bodyweight (natural) of 210lbs (years and years of bodybuilding), but at 70 inches, with the same measurements, it shows 215lbs being the maximum lean weight.

Edit: Just to clarify, I'm certain that it's more of a percentage than a number and that it happens to be 5 lbs at around my height - a 4'll" woman might only differ 2-3 lbs at a similar build from a 5'0" woman.

Sure, what you described actually weights exactly 0 pounds.

But in general the volume of a sphere grows with the cube in regards to the radius, thus gaining an inch of height could add a lot of mass. How much depends on the object shape.