If the National Football League is the family it would have us believe, the teen-agers have ransacked the house. They were nearly stillborn, scarcely given any chance to live more than a few months and seen as certain to be devoured by rivals who, in fact, later became their brothers.

By nine, they had won their first major fight with these snobbish, fratricide-inclined brothers assumed to be in the prime of life. By 15, they had muscle beyond belief. They have become more brutish each year.

The AFC and NFC are not quite the All Football Conference and the Non Football Conference, although this season suggets additional swift movement in that direction. The crack that began with the Jets whipping the Colts in Super Bowl 3 now is a gap rather like the one between General Motors and Chrysler.

Devilish whispers abound. See an NFL game, get a check. The AFC champion will use only special-teamers and still win the Super Bowl by three touchdowns. To make the Pro Bowl even this season, the AFC will start Kermit The Frog at tight end and Dolly Parton at middle linebacker.

When the AFC gained a 23-17 edge in interconference games in 1975 and a 16-12 advantage a year later, everyone in the NFC insisted it was one of those brief cycles the structure of sports not only encourages but also seems to demand.

But the AFC won the series the next year, by 19-9, and the next, by 31-21, and has the largest margin of all -- 31-11 with 10 games left -- this season. Can anyone foresee five NFC teams matching the elite five of the AFC any time soon?

In its 20th year, the AFC is tougher and swifter. Also, its best teams seem more mature than NFC teams in the '20s and '30s. They play with confidence and flair, knowing they have three ways to overcome every mistake; they are a delight to watch.

For fans who care to look beyond their hometown goalposts, there are at least half a dozen AFC teams worth serious attention each week. The NFC has one -- and part of the reason the Dallas Cowboys are so appealing is that they play like the AFC demons.

The best of the AFC is to the best of the NFC as an Indy car is to an assembly-line sedan. Recently, the NFC admitted as much, its teams searching out the brighter AFC minds (Bill Walsh at San Francisco, Monte Clark in Detroit, Ray Perkins in New York, Bobby Beathard in Washington) to help revive stagnating teams.

About now, a hand might well pop up and a loud voice ask: What about the best and brightest of the AFC teams, the Steelers, the dominant force of the '70s? They were an old NFL team, formed in 1933, that had to be kicked and coaxed into joining the AFC in 1970.

In truth, they were an NFL team but an NFL embarrassment for decades. The owner, Art Rooney, is as nice a man as sport has ever seen. And they were rugged and colorful. But losers much more often than winners.

If there was a way to misuse the most important tool in the NFL -- the draft -- the Steelers would find it.Their top choices either rarely played or rarely played well. The year before the NFL and AFL became the NFC and AFC, 1969, the Steelers were 1-13.

Flops among the older teams, they became fabulous among the newer ones, the prototype that General Manager Beathard and Coach Jack Pardee would like to copy with the Redskins, the one A. J. Foyt would fight to drive if this machine were a car.

"They've drafted well and coached well," said Beathard.

"Which is correct of course, but inadequate, like saying Frank Lloyd Wright built nice homes. Because player movement is so restrictive, building and maintaining an NFL team is the most difficult of all the major pro sports. Only the '60s Packers and the '50s Browns have done as well or better than the '70s Steelers -- and they had less competition, quicker access to the better players in the available drafting pool.

Where the elder Rooney and his cronies could hardly tell the difference between a quarterback and a quarterhorse -- and, in fact, seemed to prefer the latter -- his sons and Chuck Noll have done unimaginably well with the draft. They have been nearly flawless in the first three rounds for the last 11 years.

"We've got the weapons," said the original cornerstone, defensive tackle Joe Greene, the No. 1 pick in 1969. "And we've got the fort. The offensive line is the fort. You sit and fire your weapons from the fort.

"I know how we prepare for people, how we'll look two and three plays ahead so we can attack better. Flip it around. I've played against teams who don't know what in hell we're doing. And we're supposed to be playing against such a high level of competition."

The personnel wizzards drafted Greene, Terry Bradshaw, Franco Harris, Jack Ham, Lynn Swann, J. T. Thomas, Jack Lambert, Bennie Cunningham, Robin Cole and Sidney Thornton in the first or second rounds.

The coaches developed a 10th-rounder named L. C. Greenwood, an 11th-rounder named Mike Wagner and a Vietnam veteran with a bad leg, Rocky Bleier.

Luck has been a factor. The Steelers were said to be frustrated to the point of nearly trading Bradshaw during his early, erratic years. And Noll had to be persuaded to choose Harris over another fullback, Robert Newhouse.

"There are a lot of people in this country apologizing for winning," Noll has said. "Not so much in football, but in life. There seems to be a drive toward mediocrity in this country. There used to be rewards for being first . . ."

A lot of people insist the recent NFL changes in scheduling and rules -- known informally as Pete's Parity -- act unfairly toward the Steelers. They believe it creates galloping mediocrity, stifles innovation, penalizes success.

I disagree.

Much of pro sports rewards incompetence, but the scheduling format -- where the best teams are forced to play each other -- separates the excellent teams from the good ones. And the changes that have aided offenses came at a time Noll was prepared to attack from that Steeler fort with verve.

During Noll's years, the Steelers seem to have quietly shifted their dominant areas, from the line to linebacker on defense and from the run to the pass on offense. All of this was mentioned to Greene and he rolled his eyes, as though thinking you can carry this theoretical nonsense too far.

He said, firmly: "It's all of us together."

Together, the Steelers have forced both the AFC and NFC to get cracking. They have won when some of the odds have been stacked against them. That makes them even more special, for the NFL, like the U.S. Golf Association during the Open, is not trying to penalize excellence but merely trying to find it.