So fervent is the interest in Jim and John Harbaugh that the rest of the family — parents Jack and Jackie, and sister Joani — held a Super Bowl conference call last week. The most probing reporter’s question came via “John from Baltimore.”

“Is it true that both of you liked Jim better than John?”

Stunned silence finally gave way to laughter.

It was John Harbaugh. Joani recognized the voice just as Mom was “ready to come right through this phone,” Jack said.

“That’s the fighting spirit,” John from Baltimore said.

And that’s the Harbaugh family. Tempting as it is to dismiss the brotherly angle as an over-hyped distraction to Super Bowl XLVII — as Jim has tried to do — the funny tales about the boys’ upbringing go a long way to explaining how the 49ers and Baltimore Ravens ended up here.

They paint a vivid portrait of how two hypercompetitive brothers with contrasting personalities — the volatile Jim, the personable John — set out on different paths only to arrive at the same destination.

Stories from the family and those close to them show that, and they take us to the root of this family tree.

For the record: No, the parents don’t like Jim best. “I know one is going to win and one is going to lose, but I would like for it to end in a tie,” Jackie said. “Can the NFL do that?”

Nope, sorry.

As with Jim and John’s previous meeting, there will be equal parts happiness and heartache. Last Thanksgiving, in the first meeting between NFL head coaching brothers, the Ravens thumped the 49ers 16-6.

When it was over, the parents first walked to Baltimore’s locker room and found a raging celebration.

“I thought, ‘We’re really not needed here,”’Jack recalled. “So we walked across the hall into the 49ers locker room. It was quiet and somber. I finally saw Jim all by himself, nobody around him. He still had his coaching stuff on. I realized that’s where we were needed. That was thrill of victory and agony of defeat, and I know we’re going to experience that this week.”

The road to the Super Bowl was not a straight line. The Harbaughs had an itinerant life, moving 17 times during Jack’s 43-year coaching career.

That was fine with Jim, who once informed his dad that he was ready to move after two years in Iowa because he had run out of friends.

Still, a lesson from Iowa left an imprint. Jack recalled taking the boys to elementary school on a cold winter day and turning around to see his boys shivering in the back seat.

“I saw their faces, their sad, sad faces,” Jack said. “And our thing was: ‘We will attack this day with an enthusiasm unknown to mankind! And oh, by the way, don’t take any wooden nickels.’ ”

The wooden nickel part is long gone, but “Attack this day with an enthusiasm unknown to mankind!” is a staple in the 49ers’ locker room. It was one of the first things Jim Harbaugh said when introduced as the team’s coach.

Jack called the boys’ decisions to choose coaching careers even after seeing the strain it can take at times, “the greatest joy” of his life.

At youth hockey games, Jackie began sitting away from other parents because her boys kept plowing over other kids. As a youth pitcher, Jim once plunked a girl in the back — bringing her angry mother onto the field to accuse Jim of being a bully.

“She was crowding the plate,” young Jim reasoned.

Jackie eventually got called into the elementary school in Ann Arbor, Mich. There were complaints from parents about both, though mostly Jim, playing too hard at recess.

“Jackie told (school officials): ‘You do everything in your power to make sure he’s a good sportsman out there. But don’t do anything to affect his competitiveness,’ ” Jack remembered.

That sounds exactly like Jackie, said Willie Taggart, a family friend who is the South Florida football coach.

“Jackie is really the head coach of the Harbaughs,” he said. “I think even Jack gets his competitiveness from Jackie. She is just tough, and that rubs off on everyone else.”

Heaven was going to Dad’s practices. At Michigan, the brothers were taped to the goal posts and stuffed in lockers by players, and loved it. They collected used wristbands and would write No. 7 on them — the number of Wolverines star quarterback Rick Leach — and sold them to gullible classmates for a buck.

One day, Jim cavalierly risked the wrath of the legendary gruff Michigan coach Bo Schembechler.

“When people ask what the difference was between Jim and John, Jack always tells the story about when they were 9 and 10,” said David Elson, an assistant under Jack and now the New Mexico State defensive coordinator. “The staff was coming off the field and John was right there waiting where he was supposed to be. But they couldn’t find Jim.

“So they walk into Bo’s office and there’s Jim sitting in Bo’s chair with his feet up on Bo’s desk and he says, ‘Hey, Bo, how are you doing?’ That’s Jim. He has a little more of a devil in him than John.”