According to Google, today is Rembrandt van Rijn’s 407th birthday. Perhaps it’s the flattering light, but to me he doesn’t look a day over 400.

Last year — when Mr. van Rijn was only 406 — I was immensely privileged to get a private tour of Rembrandt in America at the Minneapolis Institute of Arts. One of the central themes of the exhibit was, “Is that Rembrandt really a Rembrandt?”

It may seem a silly question, but I learned it’s actually a sticky one: Of the 50 “Rembrandts” in the exhibit, only 30 are now attributed to the great master. The rest? Well … there lies the rub.

In Rembrandt’s day, it was common for the master to sign an apprentice’s painting after adding a finishing touch. In other cases, Rembrandt never even touched the painting. It was enough that it had come out of his studio — and that some wealthy patron had eagerly shown it off — for the painting to take on its priceless reputation.

I was very moved to walk through room after room of stunning paintings (regardless of their authorship). But the painting that most touched me was, ironically, the one I’d barely noticed in previous visits to the museum. Only after learning about Rembrandt’s many hardships and heartbreaks did I truly appreciate his pathos for Lucretia.

“That’s great,” you’re probably thinking. “But what about that painting in my attic? Is THAT a Rembrandt?”

Well, I’m obviously not an expert. But — based on what I learned last year — here are five clues it may be a fake.

Happy birthday, Rembrandt.