COMMERCIAL: So cuddle your baby as often as you can. With the right start, you can be in touch for the rest of their lives.
SUSAN DENTZER: An entire industry has cropped up in recent years, bombarding parents with advice on raising their children.
COMMERCIAL: So sing to your baby.
COMMERCIAL: At three months you might consider reading to your baby.
COMMERCIAL: Be cautious during toilet training. Your child will see the toilet as another opportunity to explore.
SUSAN DENTZER: Many moms and dads pay strict attention. Make one false parenting move they fear and little Johnny and Mary may be ruined for the rest of their lives.
SPOKESPERSON: And with a magic flick of the wrist, things disappear.
SUSAN DENTZER: Even Hollywood has spoofed the obsession with perfectionist parenting, as here in the movie "Parenthood."
PARENTHOOD MOVIE CLIP: FATHER: And see, Grandma, Patty studies Eastern Philosophy. Our future leader is going to have to be much more in tune with the oriental mind. One more time.
MOTHER: Nathan, guess what?
FATHER: Boy, you're home early. (GIRL PUNCHES FATHER)
SUSAN DENTZER: For years, conventional wisdom has held that all this parental nurturing will definitively shape a child's personality and behavior. In a recently published book, author Judith Harris calls this belief "the nurture assumption," and she says it's just wrong.
JUDITH HARRIS, Author, "The Nurture Assumption:" It's the assumption that what makes children turn out the way they do, aside from their genes, the environmental part of child development, is the experiences they have at home, and in particular the experiences they have with their parents.
SUSAN DENTZER: Harris argues that besides passing on genes, parents' nurturing probably has less impact over the long-term than other aspects of children's environment - such as their peers.
JUDITH HARRIS: It's really in the second half of the 20th century that this idea of parental importance has become so popular and, in my view, exaggerated. I'm not saying that parents don't matter. I'm saying that parents matter in some ways and don't matter in other ways, and we have to look and study where they do, and where they don't matter, and not assume that they matter everywhere without scientific justification for it.
SUSAN DENTZER: Harris's book has lobbed a grenade into what might be called the "parenting establishment" - the legion of experts offering advice on everything from limiting television to controlling tantrums. Her ideas have prompted critical news coverage and commentary - as well as condemnation from child development specialists. One is researcher and practicing child psychiatrist Dr. Stanley Greenspan.
DR. STANLEY GREENSPAN: The biggest worry about this book, it's going to tell parents it doesn't make a difference what you do. It doesn't make a difference if you are loving, if you are warm, if you are intimate. So the worst part of this is that parents - I think most parents are too smart for that - but that any parent believes the message, they could devalue what's so important about what they do give to their children - the love, the warmth, the security, the building blocks of healthy self-esteem, healthy thinking, and healthy patterns of communication.
SUSAN DENTZER: By contrast, psychologist Steven Pinker of the Massachusetts Institute of Technology thinks Harris's work is a turning point in developmental psychology.
STEVEN PINKER: It's a shocking discovery. It's one that I think most people would not have predicted. It poses a question, how do we explain this very large component of personality that's not genetic but that just as surely doesn't come from growing up in a particular home?
SUSAN DENTZER: Harris would seem an unlikely warrior to mount an assault on the parenting industry. She is a mother of two daughters, a grandmother, and a writer of psychology textbooks. She was tossed out of a psychology graduate program at Harvard more than three decades ago because her professors didn't think she'd amount to much. In effect, she has now waded into an age-old controversy: What makes the difference in the way human beings turn out? How much is nature, that is, genes, or nurture, the way that your parents bring you up. Researchers have long struggled to define the relationship.
STANLEY GREENSPAN: Nature/nurture work more as a dance, not as a horse race. But it's really like Fred Astaire and Ginger Rogers. Once the dance starts, it's how they interact together.
JUDITH HARRIS: You can certainly look at Fred Astaire separately from Ginger Rogers. Of course, they dance together. Nobody questions that they dance together. But it is possible, using certain techniques, to tease them apart and to look at them separately.
SUSAN DENTZER: In fact, researchers have been doing just that for years, and in the process have found a decisive role for nature or genes.
STEVEN PINKER: The behavioral geneticists did that with studies of adoptees and twins and found that virtually all of the correlation between parents and children, comes from their genetic similarity, that is, if you look at two kids who grow up in the same household, they are no more similar than two children who grow up in different households, on average, in their personality.
SUSAN DENTZER: Behavioral geneticists have concluded that about half of the variation that crops up among people is due to heredity, in other words, to their genes, but that leaves about one half of these variations unexplained. It's long been assumed that these must stem from the other partner, nurture or parenting. But Harris says this partner may have been a victim of mistaken identity - the result of faulty research by child development experts.
JUDITH HARRIS: They were producing results that showed that parents who read to their children, parents who were themselves educated, and who were interested in educational achievement and educational enrichment of their children, they were finding results that showed that such parents did have smarter and brighter kids. The problem was they weren't - their techniques weren't able to distinguish between genetic influences and environmental influences. It was assumed just without really any basis in fact, it was assumed that it was because of the parenting.
SUSAN DENTZER: In fact, Harris concluded that the other partner dancing with nature wasn't parenting, but rather forces at work in the broader environment that children grow up in. She came up with something she calls "group socialization theory," the notion that children's peers, along with other groups that they might become involved in, are the factors in addition to genes that help to shape personality and behavior. Harris believes that research on the children of immigrants provides one of many clues that she's on the right track. She told us the story of a child she called Joseph.
JUDITH HARRIS: His parents came from Poland, and they settled in a rural area of Missouri where they were the only people from Poland, and no other people spoke Polish. In a year or so Joseph was speaking English like an American, and he's going to adopt the culture and language of his peers, even though he continues to speak Polish at home with his parents.
SUSAN DENTZER: But Stanley Greenspan believes Harris has misinterpreted the research on immigrants and understated the crucial role of parents in stimulating early language development.
STANLEY GREENSPAN: Completely mistaken, completely naïve. Children learn the structure of language from pre-verbal communication, from the rhythm of utterances. Later on, once you have that, you can learn a new language but the fundamental ability to relate and think itself has learned very early in life before peers are even important.
SUSAN DENTZER: But Harris still insists that the parenting establishment underplays what every parent of a teenager knows - that peers really do have a determining impact on personality and behavior. Along with Professor Pinker, we decided to talk with some MIT students about the respective influence of their parents and their peers. Senior Leslie Pipe told us that she was close to her parents and believed that they had profoundly shaped her - at least until she went away to college.
SUSAN DENTZER: So what inspired you to have blue and purple and beautiful red hair?
PIPE: It was sort of a rush activity for my dorm, to try to get kids in my dorm.
SUSAN DENTZER: What is the message it sent
PIPE: Dare to be different, I guess.
SUSAN DENTZER: Dare to be different by looking like me?
PIPE: Right. (laughing)
SUSAN DENTZER: The mother of another MIT student, Paula Goldstein, came forward to tell us about her two sons - the MIT senior and her 28 year old elder son, some she described as "not accomplished." She asked whether her parenting could explain the difference in her two sons.
STEVEN PINKER: Anything that is consistent the research suggests doesn't have a long-term influence on the personality of the kids when they grow up.
PAULA GOLDSTEIN: So then it's not my fault. I want to be responsible for the kid who's graduating MIT, though.
JUDITH HARRIS: Well, I think this parent has really answered it for herself. If she wants to take the credit for child A, she also has to take the blame for child B. I'm saying, well, you can't take the credit, but on the other hand, you don't have to take the blame.
SUSAN DENTZER: Harris says parents can do things to affect how their children turn out - help them choose the right friends, for example.
JUDITH HARRIS: All parents know this, and they've been doing this for a very log time, and they've always tried to do this, to move to the right neighborhood, to put their children in the right school.
SUSAN DENTZER: She even suggests that parents make sure some children get plastic surgery, so they will fit in.
JUDITH HARRIS: Only if the child has some facial anomaly that will evoke teasing from peers. A child can be made very miserable by being teased over something that he or she can't help.
SUSAN DENTZER: It's this kind of advice to parents that disturbs critics like Greenspan.
STANLEY GREENSPAN: The advice is terrible because she also goes further and says have plastic surgery, if your nose is too long. It totally presents a kind of conformist view, conform to the peer group and you'll be okay.
SUSAN DENTZER: Harris admits that her theory of group socialization is just that - a theory that merits further research and exploration. Until that research is in, she counsels parents to enjoy day-to-day parenting more and worry about its long-term effects less.
JUDITH HARRIS: I think that parents are spending every free minute of their time reading to their children, and praising their children, and hugging and kissing their children, and still feel that's not quite enough, and I'd like them to lighten up a bit.
SUSAN DENTZER: But Harris says this advice and her research shouldn't be misconstrued to undervalue parenting.
SUSAN DENTZER: I'm a mother of two young boys. Am I chopped liver?
JUDITH HARRIS: No. You are essential to your children's happiness. You have the power in your hands to give your child - children a happy childhood, and I hope that you will give your children a happy childhood, because every child deserves that.
SUSAN DENTZER: Even if they object to some of Harris's other views, parents will probably agree with her on one thing - whether or not they control their children's tomorrows, they surely control their todays.