Robert De Niro’s wife, Grace Hightower, isn’t ruling out the possibility that vaccines caused their 18-year-old son Elliot’s autism. “There are many people who will come out and say ‘I saw my kid change overnight,’” the Oscar winner said during a Wednesday, April 13 appearance on Today.

“Is that the experience you had?” asked host Willie Geist, to which De Niro replied: “My wife says that. I don’t remember. But my child is autistic. And every kid is different.”

The Bad Grandpa actor, 72, who was promoting the Tribeca Film Festival (he’s a cofounder) spent most of the segment defending the controversial film Vaxxed, which was pulled from the lineup back in late March. “I think the movie is something people should see,” he said. “I, as a parent with a child who has autism, am concerned. I want to know the truth. And I’m not anti-vaccine, I want safe vaccines.”

When the hosts pointed out that there’s broad scientific evidence that vaccines don’t cause autism, he answered: “I believe it’s much more complicated.”

De Niro went on to say that he “regrets” withdrawing Vaxxed from the festival.

Discredited doctor Andrew Wakefield directed the film. In 1998 he published a paper in medical journal The Lancet suggesting a link between the measles, mumps and rubella vaccine and childhood developmental delays, but no other researchers have ever been able to replicate his findings. Wakefield’s paper — based on just 12 subjects— was rescinded by the journal in 2010, and he was barred from practicing medicine in the U.K. after the General Medical Council charged him with dishonesty and abusing developmentally challenged children.

Autism affects 1 in 68 children in the U.S., but repeated studies involving more than 1 million subjects (as opposed to Wakefield’s 12) have found there is no evidence to link childhood vaccines to autism.

The Tribeca Film Festival, which opened April 13, was founded by De Niro and producer Jane Rosenthal in the wake of 9/11 as a way to try to revitalize New York City, particularly its downtown.