Window Crank Knob Color

[ZLP955]

Original GM clear knob window crank handles, including the ones in my car, all seem to be yellow-ish, like the one in the picture below. The reproduction handles with clear knobs are quite different, er, clear, just like the description.
So is the yellowing of originals due to age, UV exposure etc, or am I missing something? Even the supposed NOS handles that I've seen (even those still in their boxes) appear to be yellow.

[Everett#2390]

You are correct, age and outgassing of the solvent. Another crutch is the recipe and lack of a better product due to technology of today as compared to the day they were made.

[ZLP955]

Thanks Everett.