Katrina La Throp recalls the time a man "stared real hard" at her toddler, Chai, and asked, "What's his father?"

"Human," La Throp answered.

La Throp is African American. Her husband, Shimon Van Collie, is white.

Such encounters are rare - they live in Berkeley, where, Van Collie said, the "quintessential baby looks exactly like Chai."

But they aren't naive about the challenges their son faces in a racially fractured society.

"He's going to have to be a really strong individual because he will get racism from both sides," La Throp said. "So we have to be conscious about how he's socialized. We want him to have a balanced perspective culturally - not totally Afrocentric, not white-dominated. It's a struggle we're dealing with right now."

The story is familiar to America's 1.2 million interracial couples, whose numbers have tripled since 1970, according to the U.S. Census.

Most dramatic has been the proportional increase in black-white couples, from 65,000 in 1970 to 231,000 in 1990.

While interracial couples remain a fraction of all American marriages, they have been highly visible in multiracial areas like California.

From 15 to 20 percent of couples in California are in mixed marriages. For certain groups, the figure is much higher. Fifty-five percent of Japanese Americans and 40 percent of Chinese Americans marry outside their group.

It was only in 1967 that the U.S. Supreme Court struck down laws banning interracial marriages. Twenty-eight years later, accelerating intermarriage is producing a population of mixed-race Americans who are blurring racial and ethnic lines.

Census figures show the trend. In 1968, 22,000 mixed-race babies were born in the United States. In 1989, 110,500 mixed-race babies were delivered.

"More than anywhere else, the United States is in the midst of a massive cultural and social metamorphosis in its attitudes toward intermarriage," says Bay Area psychologist Joel Crohn in his recent book "Mixed Matches," which delves into creating successful interracial, intercultural and interfaith relationships.

He says the biggest challenge these couples face is raising children.

"Kids are the ultimate test - they point the way for us to grow," said Crohn, whose practice in San Rafael and Kensington specializes in cross-cultural relationships.

In a recent interview in his Kensington offices, Crohn said multiracial kids quickly become aware of the world's curiosity about them.

"They get confronted with, "What are you?' a lot," said Crohn.

Cultural identity is a major issue for many mixed-race people, said psychologist Jewell Taylor Gibbs of UC-Berkeley's School of Social Welfare.

"The central issue for racially mixed people is that of identity - how do you define yourself in a society where everybody fits into boxes?" she said. "If you're half white and half black, or half Asian and half Mexican, where do you feel you belong?"

Not that multiracial kids grow up to be unhappy. Mixed-race youngsters grow up no differently than their monoracial counterparts and, in fact, often act as bridges between cultures.

But there is a natural ambivalence many multiracial youngsters feel about their mixture, and parents should respect that, Crohn said.

"Some kids play with it," Crohn said. "One day, they're black. One day, they're white. A lot of it has to do with their physical appearance, where they live and how their parents deal with race."

Parents should confront their own cultural confusion before they can help their children deal with their own identities, Crohn said.

"Each partner has to face his or her own mixed feelings about their past," he said.

For most mixed-race kids, questions about identity don't come up until adolescence and young adulthood. For some, it's a process that's still unfolding.

Mikko Jokela, 21, a UC-Berkeley junior, has a Chinese mother and a Finnish father.

With his dark hair and eyes, Jokela said he is "more easily placed as Asian." His biracial roots, however, never provoked much thought.

"I was always, in my eyes and other people's eyes, the half-Chinese, half-Finnish kid," said Jokela, who grew up in the mostly white San Diego County beach town of Del Mar. "I mean, my parents never sat me down and said, "OK, you're from a mixed race.' So I hadn't really addressed it that much."

Then, while a junior at Cal, Jokela took Ethnic Studies 150, a course titled "People of Mixed-Race Heritage." It opened up a new way of seeing himself.

"When people are always thinking about themselves along racial lines, you start to wonder, how do I fit in that society?" Jokela said. "That class tells you - it gives you history. That's something we don't have as a mixed-race community."

Jokela is now active in mixed-race issues and will be the next president of the campus Hapa Issues Forum. The group was formed a few years ago by students who were "hapa" - a Hawaiian term for those who are half Japanese and half white.

The forum sponsors conferences, workshops and discussion groups. On picture day, members share family photos.

"You see kids who had blond hair when they were three years old," Jokela said. "It's weird how you pick up different traits. It's really interesting to see people's parents. It's like taking two colors together to see what you're going to get, like experimenting with your Crayolas."

There is, Jokela noted, a "fascination with the visual, because so many of the issues are based on visual characteristics."

That only reflects society's obsession with physical appearance, said Taylor Gibbs.

"Race is a very unscientific concept - most people are mixed in one way or another," she said. "So race is a social construct. People look at you and define you by certain physical features and by your hair. That's how you get defined by what race you belong to."

For multiracials, that prompts the question, "What are you?"

But Cynthia Nakashima, who teaches Ethnic Studies 150 at UC-Berkeley, said that question isn't as common in the Bay Area, especially when it comes to Eurasians.

"I think the whole society in the Bay Area are much more used to what we look like," said Nakashima, who is half Japanese and half white.

Yet that acceptance sometimes translates into what she calls "everyone's favorite stereotype" - the nearly cliche notion among Americans of both Asian and European ancestry that mixed-race people are especially attractive.

Nakashima said that notion is "wrapped up in the whole thing of a white, anglicized version of people's color being more attractive" than the its pure, unmixed form.

The idealization of "exotic" mixed-race people "puts a lot of pressure on people," especially women, Nakashima said.

"I know one woman who's Russian and Japanese who doesn't feel she's pretty. She tells me, "I feel like I'm missing one of the important qualifications for being hapa.' "

Nakashima said multiracial people also face other difficult issues in relating to their parents' cultures.

She cited, for example, parental heritage rules for the Cherry Blossom Queen contest and community athletic teams.

"One of things they say about the Cherry Blossom Festival is that if a person is below one-half Japanese, they don't "look Japanese' enough to represent the community," Nakashima said. "The problem with that is that there's a lot of variety in the way mixed-race people look. It's a real can of worms and community officials don't want to get into it."

For African Americans, the mixed-race issue carries other cultural baggage.

"For African Americans, there is a feeling that being African American has always had a certain stigma attached to it," said Taylor Gibbs. "When people are racially mixed and want to deny their African American heritage, black people find that very, very offensive. It's as if the person who is only half African American wants to reject that side of his heritage and identify with the other heritage. And yet, society looks at that person and assigns him as a black person."

Taylor Gibbs said biracial people should be able to "live in their own worlds. I don't think people should be forced to accept a racial category they don't themselves want to accept. But society forces people into boxes."

And those boxes are coming to have statistical weight, Taylor Gibbs said.

An issue being fiercely debated is a new census category for multiracials - controversial because some feel it would dilute the political power of minorities, especially blacks.

"There is a political consequence to how you define yourself," said Taylor Gibbs.<