Gene
A gene is a portion of a DNA molecule that contains the information needed to build a particular protein. The idea of the gene, though, is older than our understanding of DNA. So, the original definition of "gene" just meant some hypothetical substance that a living thing has that can be inherited and that determines a particular trait (like height, color, etc.). Money would probably fit that original definition, especially if the trait in question is "ability to purchase more shoes than one needs," so it's a good thing they changed it.