My dad told me that I shouldn’t try it. With just $400 in my pocket, no maps, no ability to speak Portuguese, Spanish or French, I wanted to ride my bike from southern Portugal to northern France. I was 18 years old.

“It’s just not a practical thing to do,” my dad had said. And he was right. I got into a pretty tight jam during that trip. I ran out of money. Some nuns gave me cash when mine ran out.

Fathers are usually more practical than sons. Life experience helps. But children like to forge their own paths—to find out for themselves. Perhaps that’s what John Bogle’s son tried to do.

John Bogle is the champion of index fund investing. His son—who’s also named John—runs the actively managed Bogle Small Cap Growth Investor Fund (BOGLX).

The older Mr. Bogle says investors should stick with low cost indexes. Active management, he argues, rarely wins after fees. The 86 year old proves his point in a few classic books. One is Common Sense On Mutual Funds. A shorter version of the first is The Little Book of Common Sense Investing. Both show the reader, through reams of evidence, that active managers rarely overcome the fees they charge.

Bogle says that market-beating funds do exist. But one decade’s winning fund often becomes the next decade’s loser.

Sometimes managers hit a lucky streak—before their fortunes falls flat. Brad Steiman, of Dimensional Fund Advisors figured out how many years a manager would need to beat the market before his success could be deemed skill, and not luck. He says it takes thirty-six years. “Based on these parameters,” says Steiman, “by the time you are reasonably confident there is some amount of skill, the manager is likely retired and on her yacht!”

In 2013, The Wall Street Journal profiled the two Bogle men. The younger Bogle’s fund had thrashed its comparable small cap index. Liam Pleven wrote, “[The] Bogle Small Cap Growth Fund was launched 14 years ago and has delivered an annualized return since then of 12.4 percent, compared with 8.6 percent for its benchmark index.” Was the younger Bogle skilled? Or was he just plain lucky? Based on Steiman’s assessment, Bogle required 22 more years of market beating performance before time revealed the answer.

Since 2013, two more years have passed. Perhaps time has delivered its verdict. During the past 12 months, ending September 30, 2015, the Bogle Small Cap Growth Fund dropped 11.98 percent. That compares to a loss of just 0.28 percent for Vanguard’s Small Cap Index (NAESX). This changes everything. Vanguard’s small cap index now has a better 3 year track record than Bogle’s Small Cap Growth Fund. The index also has a better 10 year return, and a better 15 year return.

For the record, Morningstar categorizes the younger Bogle’s fund as a “small blend” fund in spite of having the word “growth” in its name. So this is an apples-to-apples comparison.

John Bogle senior does own shares in his son’s active fund. As he told Liam Pleven, "We do some things for family reasons. If it's not consistent, well, life isn't always consistent." The elder Mr. Bogle may not be a billionaire. But he sure isn’t hurting when it comes to spare change. He can afford to take risks.

Most investors, however, aren’t well-heeled enough for that. When it comes to investing, long term evidence should drive our decisions.

John Bogle senior writes and speaks compellingly. He says trying to beat the market with actively managed funds just isn’t practical. But when fathers talk to sons, well…sons don’t always listen.

1 Year Returns 3 Year Returns 5 Year Returns 10 Year Returns 15 Year Returns
Bogle Small Cap Growth (BOGLX) -11.98% +11.59% +13.03% +5.83% +7.31%
Vanguard Small Cap Index (NAESX) -0.28% +12.33% +12.83% +7.61% +7.52%

Andrew Hallam is a Digital Nomad. He’s the author of the bestseller, Millionaire Teacher and The Global Expatriate's Guide to Investing: From Millionaire Teacher to Millionaire Expat.