"Oh yes." Martha nods, this time with a smile. "I married the most impossibly obstinate man on the face of the earth. And being quite stubborn myself, we managed to raise the second most impossibly obstinate man on the face on the earth. It's quite astonishing really. And Clark doesn't even have our genes. You can imagine if..."

She trails off, immediately closing her eyes and wincing. Sometimes even she had the power to hurt herself by bringing that up.