kneeling

So, I'm the grandson of a Danish immigrant who survived Pearl Harbor and went on to survive other attacks. The son of a 22 year navy/army vet who served two tours. A nephew of two uncles who served. I am an Army veteran of four years and a 9 month deployment. I put my hand over my heart every time I heard the national anthem before I enlisted. I've stood at attention every time thereafter. I know my country isn't perfect and I have zero problems with someone kneeling. What's the deal?