Yeah it's probably simply indicative of gun attitudes in the states. Heck, Mississippi is probably overstated because some people are too ashamed to admit they DON'T have a gun
(Mississippi's State Motto is
Virtue et Armis - by Valor and Arms)
But Texas has a reputation to uphold after all! You wouldn't Texicans would be shy about owning up to having a gun in the house. Houston is probably skewing the numbers.
Maybe the only thing the survey shows is that states with mainly rural populations have a higher percentage of gun ownership (or a higher percentage willing to admit to gun ownership) than states with big cities. DUH!