Do you think more people know of Conan's identity than we are told?

[tengaku squared]

Yes, but Kogoro is exceedingly lazy.

Kogoro isn't lazy when the situation calls for it, he's actually a frighteningly effective detective in dire situations. However, I'm very sure that Conan's identity isn't the first thing on his mind, so he just brushes it off as a kid being smart-aleck.

Besides, to him, Shinichi and Conan aren't linked in the slightest, so he wouldn't think "Hmmm, maybe this kid is actually that Shinichi brat". The mere fact that Shinichi somehow shrank into a 7-year old Conan defies any standard logic.

[Silverbullet-kun]

Sera, Amuro, Okiya