A good time not to rely on the experts is when what they tell you is palpably ridiculous.

In Wednesday’s column, the Sun-Times‘s Richard Roeper offered a little amplification. He allowed that the day before (actually two days before), “I made light of media reports that referred to Kentucky Derby winner Mine That Bird and Preakness winner Summer Bird as ‘half brothers,’ as if they were in a cartoon.” His jokey point had been that just because their dams enjoyed a quickie with a common sire, that didn’t mean the two colts regarded each other as family.

Now he’d been fully edified. He explained, “A number of horse-racing experts contacted me and said the ‘half brother’ label doesn’t apply to those thoroughbreds.” For instance, Andy Ulrich, formerly of the Daily Racing Farm, told him, “Many people, both in and out of the horse-racing industry, believe that if a horse is sired by the same stallion they are related, [but] this is a misconception. Thoroughbred racehorses can only be related on the female side. Both [Summer Bird and Mine That Bird] were sired by Birdstone, but they are not related. To be related they have to have the same mother. Same mother, different sires means they are half brothers. Same mother, same sire means they are full brothers.”

Roeper accepted this.

But it’s nonsense. Two horses with the same sire are related whether the horse racing industry wants to admit it or not. Tell their DNA there’s no connection.

The willingness of the horse racing industry to delude itself is more evidence of how serious a problem it has on its hands with inbreeding. I refer you to a New Yorker article (registration required) published just before this year’s Kentucky Derby. Reporter Peter Boyer was discussing the death of Eight Belles, a championship filly who broke down at the finish of last year’s Derby and had to be destroyed on the track.

“The incident occasioned much introspection within the industry,” Boyer wrote. “Thoughtful people involved with racing knew that it was a deeply troubled sport, with a shrinking fan base, a battered reputation, and one intractable problem: the horses themselves. Breeding practices, motivated by the enormous sums paid for elite bloodlines, have produced a modern thoroughbred that is structurally unsound. Every horse in the 2008 Derby was related, descending from the brilliant Vanderbilt horse of the early nineteen-fifties–Native Dancer, who lost only once in twenty-two starts but had to be retired because of bad ankles. His son, Raise a Native, raced only four times, never losing, before breaking down. Raise a Native’s great-great-granddaughter was Eight Belles, who was also related to Raise a Native through two other ancestral lines.”

The 13 previous Derby winners were also descendants of Native Dancer. So were the dams and sires of this year’s Derby winner, Mine That Bird, Preakness winner, Rachel Alexandra, and Belmont winner, Summer Bird