Politics tends to run in families. Once the patriarch has established himself as a political power, his friends will often form themselves into a group, or faction, that tends to become self-perpetuating. Other members of the group -- often but not necessarily blood relatives -- will come forward to offer themselves as candidates, and the enterprise rolls on, sometimes through successive generations.

American history is full of examples. The Adamses of Massachusetts were one of the earliest, and there have been many others -- the Tafts of Ohio, the Roosevelts of New York and the Lees of Virginia, to name only three. To these have been added, more recently, the Kennedys of Massachusetts.

The political saga of the Kennedy family began, as such sagas so often do, with money. The patriarch, Joseph P. Kennedy, was a businessman -- a bootlegger, in fact, who made his pile running rum during Prohibition. But subsequent generations of the family have proved more interested in politics. One can only imagine the satisfaction old Joe Kennedy must have felt when his son John was elected president of the United States. Since then, the family's preoccupation with politics has proliferated still further, until today it is hard to imagine the American political scene without Kennedys all over it.

So it was hardly news when the late Robert Kennedy's daughter Caroline put her name forward as a candidate for the New York Senate seat vacated by Hillary Clinton to become secretary of State. Caroline's subsequent withdrawal, occasioned by questions raised about her qualifications, does nothing to undermine the central point: Yet another Kennedy was seeking that coveted seat.

You can bet that we haven't heard the last of the Kennedy family as a talent resource for Democratic politicos. Nor is it altogether unreasonable that this should be so. The Kennedys are now a well-established political brand. The public knows, in a general way, what to expect of them. They are Democrats but not liberal firebrands. Their politics tend to be moderate, as Democrats go these days, and their wealth insulates them against the financial temptations that assail so many people who are tempted to have a fling at "public service." No wonder voters are inclined to feel that, in tapping a Kennedy for public office, they are opting for a known, moderately liberal and financially incorruptible candidate.

The Republicans, at the moment, are short of comparable alternatives. The Tafts of Ohio come to mind, but there is no member of that clan currently bidding for national political prominence. There are plenty of popular political candidates in the Republican ranks, but there is no acknowledged dynasty generating attractive contenders. One possible exception is the Bush family, which, after all, can boast two recent presidents and has at least one potentially appealing figure coming up through the ranks in Texas. But it's a little early to be building such expectations very high. Nor can we count out Ohio, where the Tafts may yet again surprise us with one or more interesting possibilities.

For all the perils of a political "dynasty," there is a good deal to be said for them. As already noted, they give us a comfortable sense of continuity -- in policies, and such desirable characteristics as probity. Now and again one figure in the clan may run against type (Westbrook Pegler famously called John Roosevelt "the white sheep of the Roosevelt family"), but by and large, we feel, and rightly, that we know what to expect of a Taft from Ohio, or one of the Democratic Roosevelts from New York.

So there is something to be said for political dynasties after all. They offer us a sense of security. And if they abuse their power, as political factions all too often do, they can always be ousted by the voters.