DAN AYKROYD is in one of his favorite places: surrounded by ghosts, or at least ghost stories.

Just steps off Central Park in the Beaux-Arts town house of the American Society for Psychical Research, in a library lined with books like “Gods From Outer Space” and “Wall Street and Witchcraft,” Mr. Aykroyd is presenting his family’s supernatural bona fides with the same earnest yet vaguely ironic delivery that has sustained his entire comic career. Deadpan, he dares you to take him seriously even as he seems to wink at his own torrent of outlandishness.

“My great-grandfather, Sam Aykroyd, was a dentist, and he basically was the local critic, the local reviewer for any psychic show or act that came through his hometown in Kingston, Ontario, in the 1920s,” he said. Referring to the young women who helped build the Spiritualist movement of the mid-1800s, he added: “The people who came through his hometown were people like the Fox sisters from Rochester, N.Y., who communicated with Mr. Splitfoot, the ghost of a person who was murdered and buried in the basement of their house. And not only did they communicate with Mr. Splitfoot in the house, but they took him around the world on a tour with them. So it was almost like they were traveling with the ghost who made them famous.”

Continuing his tour through the Aykroyd family’s cabinet of otherworldly curiosities, he said, quite off the cuff: “My mother claims that when she was nursing me, a man and woman appeared at the foot of the bed, so she called to my dad, and they opened up the family album, and it was Sam and my great-grandmother Ellen Jane coming to welcome the new baby.”

He waited just a moment for the perfect downbeat: “Of course, my mother comes from the skeptical French-Canadian side of the family.” Who else could have invented the Ghostbusters, an interdimensional squad of Orkin men? Who else could have devised a supreme threat to humanity in the form of the colossal Stay Puft Marshmallow Man?