We offer a primer to the modifiability of genetic neurological disease, particularly during development. One goal is to harness several unexpected observations made in the course of experimental gene modification or therapy into an explanatory conceptual context based on biological first principles. To this end, we anchor growing, disparate reports of unusual or untoward effects to a plausible framework wherein genes exhibit different degrees of modifiability and may result, when mutated or therapeutically modified, in unsuspected consequences. We propose that genetic pathogenic variant effects and modifiability depend on the number and complexity of associated protein-protein or higher-order interactions. Thus, gene malleability may range from that characteristic of the favorably modifiable primarily structural genes that subserve relatively invariant or circumscribed phenomena such as cell shape to that typical of some transcription factors, which are less functionally predictable when altered. The latter may be expressed developmentally, in compartmentalized manner, or only intermittently and yet exert vastly ramified influences sometimes circumscribed only to select species. We also argue that genetic diseases may steer the organism toward often poorly understood biological end points and co-opt multiple processes into hardly modifiable biology. Addition or modification of genes to approximate a normal state not previously experienced by the organism may lead to further aberration due to extraneous interference with the native biology of the disease state. Therefore, an understanding as perspicuous as possible of gene function, regulation, modifiability, and biological directionality down to seemingly minute but disease-relevant consequences is a prerequisite to intervention. Although we provide some groundwork steps to such an understanding, this may occasionally prove unattainable.