I happen to read this on CNN and Riggs was just talking about siblings.

Unfortunately my brother and I have never gotten along. I was adopted, but grew up with him since I was 8 days and he was 2 1/2, so we never knew anything but a true biological like childhood relationship. We fought constantly. We probably called our parents four or five times a day while they where at work! We antagonized each other and dealt with our friends hitting on each other- his friend's me and my friend's him It was a big problem. Plus when my mom died he kinda freaked out and turned to drugs and alcohol. I went on and had a kid and went to college and got married, basically- I grew up. He has not. He has a kid that he gave up his rights to. I never even got to see him. Little E has not seen him but maybe one time- Zach maybe a couple more, but never developed a relationship. I just scare my son with horror stories about my brother to keep the boy from making the same mistakes!

How about you?

From the time they are born, our brothers and sisters are our collaborators and co-conspirators, our role models and cautionary tales.

They are our scolds, protectors, goads, tormenters, playmates, counselors, sources of envy, objects of pride.

They teach us how to resolve conflicts, and how not to; how to conduct friendships and when to walk away from them. Sisters teach brothers about the mysteries of girls; brothers teach sisters about the puzzle of boys.

Our spouses arrive comparatively late in our lives; our parents eventually leave us. Our siblings may be the only people we'll ever know who truly qualify as partners for life.

"Siblings," says family psychologist Katherine Conger of the University of California, Davis, "are with us for the whole journey."

Within the scientific community, siblings have not been wholly ignored, but research has been limited mostly to discussions of birth order. But all that's changing.

At research centers in the U.S., Canada, Europe and elsewhere, investigators are launching a wealth of new studies into the sibling dynamic, looking at ways brothers and sisters steer one another into -- or away from -- risky behavior; how they form a protective buffer against family upheaval; how brothers and sisters educate one another about the opposite sex; how all siblings compete for family recognition and come to terms -- or blows -- over such impossibly charged issues as parental favoritism.

From that research, they're gaining intriguing insights into the people we become as adults.

Laurie Kramer, professor of applied family studies at the University of Illinois at Urbana-Champaign, has found that on average, sibs between 3 and 7 years old engage in some kind of conflict 3.5 times per hour. Kids in the 2-to-4 age group top out at 6.3 -- or more than one clash every 10 minutes, according to a Canadian study.

"Getting along with a sister or brother," Kramer says dryly, "can be a frustrating experience."

But as much as all the fighting can set parents' hair on end, there's a lot of learning going on too, specifically about how conflicts, once begun, can be settled.

"Siblings have a socializing effect on one another," says psychologist Daniel Shaw of the University of Pittsburgh. "When you tease out all the other variables, it's the play styles that make the difference. Unlike a relationship with friends, you're stuck with your sibs. You learn to negotiate things day to day." It's that permanence, researchers believe, that makes siblings so valuable a rehearsal tool for later life.

Multi-child households can be nothing short of palace courts, with alliances, feuds, grudges and loyalties, all changing day to day. Perhaps the touchiest problem in most such families is favoritism.

Parents feel a lot of guilt over the often evident, if rarely admitted, preference they harbor for one child over another -- the sensitive mom who goes gooey over her son the poet, the hard-knocks dad who adores his tough-as-nails daughter. If favorites exist, however, it may not be the parents' fault, but evolution's.

The family began as -- and remains -- a survival unit, with parents agreeing to care for the kids, the kids agreeing to carry on the genes and everyone doing what they can to make sure no one gets eaten by wolves.

But the resources that make this possible are limited. Parents, despite themselves, are programmed to notice the child who seems most worthy of the investment.

At first, kids appear to adapt well to the disparity and often learn to game the system, flipping blatant favoritism back to their shared advantage. "They'll say to one another, 'Why don't you ask Mom if we can go to the mall because she never says no to you,'" says Conger.

But at a deeper level, the second-tier child may pay a price. "They tend to be sadder and have more self-esteem questions," Conger says. "They feel like they're not as worthy and they're trying to figure out why."

It's no secret that brothers and sisters emulate one another, nor that the learning flows both up and down the age ladder. Younger siblings mimic the skills and strengths of older ones. Older sibs are prodded to attempt something new because they don't want to be shown up by a younger one who's already tried it.

More complex -- and in many ways more important -- are those situations in which siblings don't mirror one another, but differentiate themselves -- a phenomenon psychologists call de-identification.

De-identification helps kids stake out personality turf inside the home, but it has another, far more important function: pushing some sibs away from risky behavior. On the whole, siblings pass on dangerous habits to one another in a depressingly predictable way.

A girl with an older, pregnant teenage sister is four to six times likelier to become a teen mom herself, says Patricia East, a developmental psychologist at the University of California, San Diego. But some kids break the mold -- and do so for surprising reasons.

East conducted a five-year study of 227 families and found that those girls who don't follow their older sisters into pregnancy may not be drawn so much to the wisdom of the choice as to the mere fact that it's a different one.