FIRST SON: George W. Bush and the Bush Family Dynasty.

FIRST SON: George W. Bush and the Bush Family Dynasty by Bill Minutaglio Times Books, $25

THE GOVERNOR OF TEXAS AND Republican presidential hopeful is perhaps the most familiar unknown in American politics. We think we know him, because his name is so well worn and his parents, the former president and first lady, have been so much a part of our lives. But the eldest of their children, affable and engaging as he appears, is someone most voters are just beginning to define.

This book will help. It is not the place to go for a clear evaluation of George W. Bush's record as governor or his manner of governing. It is skimpy on those points, which are properly the subject of much other solid journalistic work.

Bill Minutaglio, a special writer for the Dallas Morning News, does exactly what his title says, places its subject solidly in the context of his family--and that is the right place to start figuring out who and what George W. is.

He is a Bush, which means he is part of a clan which has lived comfortably at the heights of affluence and influence for four generations. One great-grandfather, Samuel P. Bush, was the first president of the National Association of Manufacturers and a close advisor to President Herbert Hoover. Another, George Herbert Walker, founded Brown Brothers Harriman, the oldest and largest private investment house on Wall Street, and was an early backer of FDR for the presidency.

The governor's grandfather was a senator; his father, a president; and for almost his entire life, favors flowed to George W., not because he sought them, but as part of his inheritance.

As Minutaglio demonstrates more fully than anyone else I have read, literally everything in Bush's resume up to his election as governor in 1994 was to a substantial degree handed to him. Schools, summer jobs, college, military service, marriage, and a succession of short-term, increasingly lucrative employment opportunities all were facilitated by members and friends of the Bush clan.

During much of that time, Bush himself was casual to the point of being lackadaisical about capitalizing on his many opportunities. He was a cut-up, a young man with many friends and few clear goals. But he was also the first son, and eventually, the expectations of his parents and the whole family broke through his natural nonchalance and he became a competitor. Less than a year after his father was defeated for reelection to the White House, George W. stepped forward as a candidate for governor of the nation's second largest state. The legacy would not be allowed to lapse.

Minutaglio offers no deep insights into the emergence of this late-blooming purposefulness. Chances are, there is no deep complexity of character to probe. But the narrative is clear and the writing is well above the level of most campaign biographies. I could discern no evident bias--either adulatory or cynical.

And there are some important clues to the character of a second Bush presidency. Anyone reading of the alienation George W. felt during his years in the Ivy League--his active distaste for the cultures of Yale and Harvard Business School--has to wonder about the prospects their alumni would have of gaining major posts in a Bush administration. I suspect they'd have to prove they were as uncomfortable with the Old School Tie as Bush himself is. And even then, Bush is likely to be more comfortable --as in Texas--with people who have bummed around in less intellectually-pretentious precincts, as he has himself.

That's the part of George W. that is distinctly different from the earlier generations. "For decades," Minutaglio writes, "the tendencies from both sides of the Bush-Walker clan had seemed to work in concert as dozens of family members moved from the most powerful academic settings, into the almost requisite military roles and then into the most influential positions in business and politics."

But a new era, he says, brings "obviously different demands, different rules." George W.'s father figured out how to follow Ronald Reagan but not how to defeat Bill Clinton. Now, as his son tries to succeed Clinton, we will find out how far the inheritance, and the differences, can carry him.

DAVID S. BRODER is a political reporter and columnist at The Washington Post.