It is possible on Scadrial to be born with ability to access both Allomancy and Feruchemy. This has been of specific interest to me lately, as the mixing of different types of Investiture has curious effects. One need look only at what has happened on Roshar to find this manifested—two powers, combined, often have an almost chemical reaction. Instead of getting out exactly what you put in, you get something new.
Ooooh
