The story, probably apocryphal, goes something like this. At a dinner party, the beautiful dancer Isadora Duncan -- a believer in eugenics, the theory that genetic improvement of the human race could be achieved through selective breeding -- approached playwright George Bernard Shaw and proposed that they have a child together.

"Think of it," she said, "With your brains and my body, what a wonder it would be." Shaw, pausing for a second, replied, "Yes, but what if it had my body and your brains?"

Unintended consequences punish, and these days Montgomery and Prince George's residents are learning that lesson the hard way.

Start with Montgomery County. To better understand its predicament, return to the 2002 Democratic primary. Back then County Executive Douglas M. Duncan (D) had a stone in his shoe in the person of County Council member Blair G. Ewing (D-At Large). Duncan and his development industry allies decided that Ewing and his ilk had to go. So they hatched a plan called "Go Montgomery," a 10-year, $1 billion, pie-in-the-sky transportation scheme that promised to end gridlock (the hot-button word of 2002). Go Montgomery was backed by a $1.3 million war chest and four County Council candidates.

Duncan's electoral catechism was simple:

Get votes from the aggrieved and money from the well-heeled by promising to protect one from the other. It worked like a charm.

Duncan passed out campaign funding to his council slate of four as though it were Christmas candy and taught them to recite their gridlock prayers, and the Go Montgomery slate swept to victory.

Fast-forward to the present. No more talk about $1 billion for gridlock relief. Now we hear about bloated county salaries and exorbitant property taxes. The loyal four and the rest of the council treated Duncan's 2006 budget as though they needed contamination suits to handle it. Michael L. Subin (D-At Large) of the former gang of four called it a "political budget, not a fiscal budget." George L. Leventhal (D-At Large), another former Duncan cohort, said, "The political climate shifted from the time he sent his budget." Leventhal might as well have called the county executive stupid.

Duncan's former allies threw in with the rest of the council to carve up the county executive's budget while silently hoping that, in return, the "tax cap now" crowd would be appeased.

"Tax cap now" is the flavor of the month. But Montgomery's most critical challenge is a synchronous one -- preserving its uncommon and essential characteristics while comfortably and honorably assimilating its burgeoning immigrant population.

Don't look for that to be a priority now, though. Duncan's laboratory-tested 2002 election proved that if special interests provide huge financial resources, the election can be had. And those interests now have their eye on Steven A. Silverman (D-At Large). Alas, ending gridlock will not be a Duncan legacy, but making the cost of running for local office prohibitive will be.

Next door in Prince George's County, well- documented problems also continue to erode vital institutions. The county often seems as though it could die the death of a thousand cuts, most self-inflicted.

An all-too-typical illustration of this was on display at a recent County Council meeting. Perhaps buckling under the pressure of yet another school superintendent's resignation as well as a rapidly rising murder rate, Council member Tony Knotts (D-Temple Hills) said, "There is nothing wrong with Prince George's County. If you don't like it, leave it." Apparently it never crossed Knotts's mind that prospective residents or business people might read his comments and think, "Yes, and if I never move in, I won't have to leave."

Unintended consequences can slip in with little notice, but that doesn't mean their effects won't be pernicious.

When Board of Education Chairman Beatrice P. Tignor named Andre J. Hornsby to be school superintendent, she said that his experience running the Yonkers school system had prepared him for the kinds of fights that derailed his predecessor.

"I think that Yonkers is a very political city," she said, and "I think Prince George's is highly political." Well the flimflam man is gone, but the stark truth of the second part of Tignor's declaration is revealing.

The two-headed monster in Prince George's -- a high crime rate and a failing school system -- began to build its power as far back as the early 1970s. Even in those days, warring political cliques rather than normal social and political institutions held sway. Three decades later, the cliques, though somewhat altered to fit the times, still dominate the county's business and political life. For 30 years the focus has been on winning the clique wars, and because that requirement has been so overriding, addressing the county's critical problems usually has taken a back seat.

Looking for the culprit of Prince George's' current misery? Listen to Pearl Buck. "If you want to understand today," she said, "you have to search yesterday." Right.

Or try a little cowpoke wisdom: "You can start a sidewinder out one way, but it has a nasty habit of circling back around on you."

The way in which decisions are framed makes a big difference to what people will decide. The million and a half residents of Montgomery and Prince George's counties should listen up, or they'll find themselves living in a state of unintended consequences.