Nothing short of gene therapy or spontaneous mutation (for whatever reason) can change you genetically. And I don't see how bone structure can change once you're past a certain age, either. You can strengthen and harden your bones and connective tissue (by nothing more complicated than exercise), and increase your musculature (or decrease it), but that's about it, so far as I know. I'm not a doctor, or a scientist (despite being fairly well educated, and particularly intelligent) so I don't know everything and maybe there's some way to make it happen I haven't heard of. I do know that some rare diseases can cause bone structure to thicken, something to do with excess growth hormone excretion (almost always caused by a pituitary tumor), that can cause adults to grow wider, but that's not a genetic change, just physiological and almost without fail, problematic to the individual's health.