How I found out.

We were 14 years old.

There was this very long, steep hill near the neighborhood, covered with all these scraggly bushes. Normally, you just couldn't run down a hill this steep. You'd easily lose your balance and fall head first into a roll.

But there were bushes! Surely we could run as fast as we wanted down the hill, and smash or grab bushes on the way down to control our descent. So we did. There was a freefall feeling interspersed between the sting of a bush whipping across your chest and legs. It was the closest we would come to an extreme sport.

The next day my friend did not show up for school. I went to his house to see him. He cracked open the door just a little, revealing the most hideous blisters up and down his entire arm, neck, and face. He looked like he had leprosy or was a burn victim. It was incredible. He would only open the door half an inch wide. "Poison Ivy," he said. "The bushes we ran through were full of poison ivy." And he slammed the door saying "Go away." He was out of school for a week.

And that's how I found out I didn't react to poison ivy. This came up recently again when my wife was helping a cat in the neighborhood. The next few days she was getting horrendous itching and swelling. We though maybe it was lice or who knows what -- but why didn't I get anything? I touched the cat, too. She finally figured it out after a few days.