Simon Cowell says he won't leave his fortune to his son

Simon Cowell
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Simon Cowell

Simon Cowell might not seem like the most charitable of celebrities. But with the pending birth of his son, Cowell is making it clear that his $350 million fortune will be given to charity rather than his children.

"I'm going to leave my money to somebody. A charity, probably—kids and dogs," he told the Mirror. "I don't believe in passing on from one generation to another."

Granted, his plans for "kids and dogs" aren't as rigorous as, say, Bill Gates' aim to use his money to eliminate malaria in Africa. But with his statement, Cowell joins a growing number of rich Britons who are turning their backs on the U.K.'s longstanding traditions of primogenitor and inheritance and instead opting to assist the less fortunate (or at least, the four-legged).

(Read more: When to tell the kids they're rich)

Cowell said he'd prefer to be remembered for helping others become successful rather than helping his kids stay rich.

"Your legacy has to be that hopefully you gave enough people an opportunity so that they could do well, and you gave them your time, taught them what you know," he said.

Charitable giving in the U.K. is 1 percent of GDP—roughly half the U.S. level. Wealthy Americans typically donate at least 3 percent of their investable assets, compared with less than 1 percent for Britons.

But as American-style philanthropy begins to spread overseas, thanks to Gates, Warren Buffett and other big givers, the British are also changing their ways.

(Read more: Rich Give Less, But May 'Invest in Solutions' More)

British billionaire John Caudwell told the Guardian last year that more and more British business people are finding that philanthropy fills a void in their lives and legacies. It all comes down to "the tombstone" question—as in what people want on it, he said.

"Here Lies a Very Successful Businessman," he said. "Doesn't really do it, that, does it? Not quite enough, somehow. You'd want something more."

Even though he has created 20,000 jobs and paid gobs of taxes "something felt like it was missing," Caudwell said. "Business ... doesn't reward the soul." Philanthropy, he added, does.

Of course, Cowell may be talking about charity as much for PR reasons as out of a genuine desire to help "kids and dogs." But whatever the reason, he should be applauded if he follows through.

—By CNBC's Robert Frank. Follow him on Twitter @robtfrank.