MIcheal,
that was a good thing posting the decay chart, it clears up the question of why granite continues to release Radon forever from our viewpoint.

However, notice that the decay chain listed no Gamma radiation, only Beta and Alpha. Dig a little deeper, as I had to, and you will find more detailed charts that list the Gamma. You will find that it is a random thing, but some of those elements are known high Gamma emitters.

"* in addition, all decays emit gamma radiation "

Look right below the U 235 and U 238 decay charts. Four scroll pages down here

Uranium Radiation Properties

As you can see, it is not easy to dig through the nuances of this field. The devil is in the details.

Don't ask me why the chart you used didn't list the Gamma, I have wondered myself.