So your reasoning for thinking there's a conspiracy to hide hormones in chickens involving the federal government, various poultry companies, and the thousands of farmers they subcontract out to, is that you saw a few chicken thighs that looked too big for their bone, and your MIL had a NDA with the company she worked for? The official explanation is "better breeding and growing conditions"[1]. Is there a reason you don't find that plausible? We can see how much of an impact breeding can make on dogs, for instance, and chickens are bred so big that they develop health problems[2]. Maybe the chicken you saw really did had underdeveloped bones relative to how big it was, but it's not because of "They must be doping them with something", it's just how they were bred.
[1] https://livestock.extension.wisc.edu/articles/the-chicken-of...
[2] https://www.vox.com/future-perfect/21437054/chickens-factory...
My MIL used to be a food scientist and spent a few years working with Tyson. She hosted a party once with chicken wings twice the size of my hand. I refused to partake of them especially since she wasn’t allowed to tell me how they got so big.