For many years, I was convinced that my father would teach me everything there was to learn--except that vital information which I really wanted to know.

Dad always made a point to share with me all the stuff his curious mind vacuumed up: about sports and books and cars and places and people. But what I really wanted to hear about was him, and, by extension, learn something more about myself.

His genes gave me my black hair and almond-shaped Asian eyes, but his heritage and life history shaped his principles--and thus many of mine as well. That I spent years not truly knowing how he felt about his life and his Asian American roots made me worry that I might never fully know and understand mine.

Later this month, Dad will retire from his job as a math teacher at McLean High School in Fairfax County. His teaching career was brief--it lasted less than 10 years--but telling because he never really accepted teaching as it is defined in American public schools. Oh, he loved the romantic idea of it: the passing of knowledge from one generation to the next. He just didn't like it in practical terms: the way it was done, or not done, as the case may be.

Before becoming a teacher, Dad had been an officer in the U.S. Army for more than 20 years, serving two terms in Vietnam and retiring as a lieutenant colonel. Imagine his surprise, after decades of military discipline, when he set foot in the classroom: unruly students used to being entertained by MTV, constant interruptions, an over-emphasis on sports and clubs rather than curriculum, meddling parents putting more accountability on teachers than their own children.

This is not to say he was disillusioned. Every evening after dinner he would disappear into his den and not emerge until it was time to go to sleep. He'd work on his lesson plans, go over his exams, surf the Internet for information he could use to keep the kids' attention. He'd bring in sports box scores from the newspapers and work them into his discussion of statistical probabilities. He'd watch the popular videos and TV shows just so he could make contemporary references in class.

"Hey, do you kids know that song 'O.P.P.'?" he once asked me and my sister.

"Yeah, it's by the rap group Naughty by Nature," we responded.

"Well, I told my students today that I'm 'down with O.P.P.,' " he said, proudly quoting a line in the song, as we privately debated how to explain to him that O.P.P. stands for Other People's P--well, to quote from the song again, "another way to call a cat a kitten."

It was just like Dad to go to absurd lengths to impart his knowledge to someone else.

Boy, do I know this. Growing up, asking Dad a simple question about, say, what color I should paint my Soapbox Derby car meant settling in for an hour-long lecture about the precise number of ounces of lead to put into the balsa wood, how to ensure the maximum pull and minimum drag on my car, and why you have to sand the front to reduce air resistance, which is created when pressure . . .

YAWN.

He was relentless.

My first memories are of my father tucking me into bed. Forget about "Goodnight Moon." This was "Goodnight Arithmetic." We'd go over the basics of counting by tens on the columns of my brass headboard--the first column were the tens, the second the hundreds, the third the thousands and . . . by then I'd be asleep.

As I got older, I developed many of my own interests. Or so I thought. Every time I delved into something, so did Dad.

When I became curious about photography, he set up a darkroom in our basement, and then he set about explaining the nuances of aperture openings, film speed and so on. When I wanted to take up tennis, he spent so much time researching the best rackets in Consumer Reports that I finally gave up and went swimming instead.

Dad never could understand why I didn't know how to change the oil in my car, work the picture-in-picture device on my television, or hook up my laptop computer to his desktop. I don't know how many times I'd ask him to set up some new electronic device for me and he'd say, "Why don't you read the manual?"

Poor Dad. It just frustrated him so much that others didn't always share his curiosity. Or maybe he just longed for us to hang on his every word. My mom used to say she thought my dad never forgave me and my sister for growing up and not remaining content to sit in his lap as he told us inflated tales--we called them "Bob-isms"--about his "days as a kid in Chicago."

But when I asked Dad about other parts of his past, he became oddly reticent.

See, before Chicago, Dad spent four years living in Topaz, Utah, during World War II. He was just a young boy, but his experiences in the Japanese American relocation camps surely must have been powerful influences on him. Not that you'd know it from talking to him.

Not once did I hear my father express any deep thoughts or any passionate feelings about his time there. No bitterness that his father lost a successful California dry-cleaning business, seized by the U.S. government when the Nakamura family was sent to the camps. No anger that after the war, they had nothing and relocated to Chicago. No regret that because he had spoken mostly Japanese in the camps, his English skills suffered at a time when he had the greatest opportunity to get ahead in school. Or that as the eldest of four children, he bore the burden of being the man of the house, while my grandfather spent 15- and 16-hour days working in someone else's dry-cleaning shop.

And, the older I got, the more I thirsted to hear it--heck, the angrier I got about his silence. Even the lone picture I found in a family album of my father revisiting the site 30 years later shows no sign of hurt in his eyes--in fact, there's a smile on his lips as he poses in front of the only remaining monument.

For years, it tormented me that my father chose to spend his life serving the very government that had jailed him as a boy. I railed against it at the family dinner table. I flirted with getting the word "Topaz" tattooed on my shoulder, complete with a Rising Sun. I became the president of an Asian American activism association. I cheered when my grandfather vowed that he would never accept the $20,000 retribution payment being discussed by the U.S. government--and I felt almost betrayed when my father quietly accepted the payment several years later.

I even started to wonder why my father chose to marry a white woman--essentially questioning my very heritage since that woman is, of course, my mother.

At 28, I have only recently begun to understand.

In a family that had lost everything, Dad was expected to fulfill his parents' dream of assimilating and becoming successful in America. First, that meant getting a college education--but to do so with no money. So he went to the University of Illinois on a Reserve Officer Training Corps scholarship. In return for the scholarship, he was compelled to spend two years in the U.S. military. He sent portions of his weekly paychecks home from Vietnam to his parents and his three younger siblings.

Two years turned into five, and, with his siblings going to college, Dad felt compelled to keep sending money home. Soon my father was married, with children. And so Dad never had the opportunity to follow his dreams: His steady, dependable military pay would allow his children the kind of freedom to choose a life that he never really had. Before he knew it 20 years had passed, and then he was retiring from the military and retraining for a similarly safe job as a public school teacher to fund my sister's and my college tuitions. There's no telling where his immense curiosity would have led him had things been different. But I doubt my dad gives that too much thought. Like his career, Dad's life has been about discipline, honor, duty and responsibility. Not to his race, or his country, but to his family.

If his single-minded purpose ever made him seem pedantic, or out of step, I have begun to understand that it also revealed the answers I so long have been seeking, and taught me everything I needed to know about my father.

CAPTION: Robert Nakamura and David in an Army apartment in Germany.