He said the real concern with sword swallowing is not so much about ingesting the blade, but what that blade is made of.
"You have to make sure it's made out of the proper metals because otherwise it can make you sick," he said.
It's concerns like these that prompted Penney to teach his sister how to swallow swords.
"I didn't want her to hurt herself, so I thought it was best to teach her," he said. "She swallowed her first sword in 2010 and her main reason for doing it is because I could and she doesn't want to be outdone by her brother."
Unlike Laura, who does this as just a hobby, Nick swallows swords for a living. Along with his magic shows, sword swallowing and other side show entertainment tricks are his main source of income. Once in awhile Laura will perform alongside him.
"It's a rare thing. There's only 42 of us in the world who practice this art," said Penney. "I can swallow multiple swords and do a cart wheel, and I hold the record for swallowing the most swords under water - which is three."
But despite his unique talents and love for this type of entertainment, Penney does not encourage others to try sword swallowing.
"No, it's dangerous. I don't recommend people risk their life for it. I recommend people become a doctor or nurse and take care of me when I hurt myself doing these things."
For more information, log on to www.MaineSwordSwallower.com.