Also check the overflow recovery tank to see if it looks dark and dirty. If it's a head gasket leaking then the cap should be venting the excess pressure (combustion gas and blow by) back into that tank. You should see it bubbling inside the tank when the engine is running. As above the idea is that the cap gives before you blow something so I'd really think this is a long shot.
Check your motor mounts to see if the engine is rocking and pulling on the hoses. If the cracks are anywhere near the hose this is a good culprit. Hood open, engine running, put it in drive and slowly do a brake stand and see it the engine starts to twist excessively. Then do it in reverse.
Did they crack in a similar place? If so it's doubtful it's the radiator itself. It could be but I'd be looking for something that damaged the radiator if they cracked in the same place. You might want to check the mounts themselves and make sure if it's rubber mounted the rubber is there. It'd take a lot of twisting to crack one but ... maybe.