Pierce Brosnan may be unlocking the secret to why Irish men seem to possess enviable mops of hair.

“I don’t know,” he told Page Six exclusively at the premiere of “The Thursday Murder Club” on (naturally) Thursday evening in New York when asked his theories.

“It’s all in the hair, the old Celtic hair,” he shared before noting that his father, “Dear Tom…had good hair.”

The “Mamma Mia!” star opined that perhaps “potatoes, butter,” or “the Guinness” was responsible for the lack of baldness among older Irish gents.

And when we told Brosnan he seems to be aging like fine wine, the actor replied, “I’m doing my best!”

The actor, 72, will soon be seen in the charming murder mystery on Netflix opposite Ben Kingsley and Helen Mirren, in which he plays a slightly rough-around-the-edges former

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