In fact, the study found that sibling violence is a predictor of dating violence and is compounded by the experience of growing up in families where parent-to-child violence or parent-to-parent violence exists, said Virginia Noland, a UF professor of health science education.
"The findings suggest that sibling violence - the most common and least understood form of family conflict - is not harmless and may be an important influence later in violence between intimate partners," she said.
"The results are significant because so many of us have siblings," Noland said. "And today, with all the divorces and remarriages in our society, there are also stepsiblings, so even an only child can end up being a sibling via a second marriage."
The survey of 538 men and women at a community college in Hillsborough County, where Tampa is located, found that dating violence was more common among partners who had punched, shoved or otherwise abused their siblings than those who had not, Noland said.
The study examined conflict behaviors occurring between the ages of 10 and 14, when sibling violence peaks, she said.
"After the older sibling reaches 14, they tend to gravitate to their peer group and spend less and less time with their brothers and sisters," said Noland, whose research appears in a supplement to the March/April 2004 issue of the American Journal of Health Behavior.
Siblings learn violence as a form of manipulation and control as they compete with each other for family resources, Noland said. They carry on these bullying behaviors to dating, the next peer relationship in which they have an emotional investment, she said.
"By that time, they've practiced these behaviors, they've perfected them and now they can use them quite well," she said.
Survey participants were given the Conflict Tactics Scale, a well-known instrument that measures how people are affected by their experience with violence. The written survey of 144 questions looked at both the respondents' experiences as a victim and perpetrator of violence, asking about conflicts involving sibling-to-sibling, parent-to-parent, parent-to-child and date-to-date.
More than three-fourths - 78 percent -- reported being pushed or shoved by a sibling, while nearly as many - 77 percent - said they had pushed or shoved a sibling. Fifty-five percent said their sibling punched or hit them with something that could hurt, while half said they had done this to their sibling. A quarter reported being slammed against a wall, and 27 percent said they had done the same to a sibling, she said.
Overall, 9 percent - 10 percent of men and 8 percent of women - said a sibling had used a knife or gun against them, while nearly 6 percent overall - 5 percent of men and 6 percent of women - reported using a knife or gun against a sibling, Noland said.
The highest level of sibling violence was found between two brothers and the least between two sisters, Noland said.
"Females admitted to perpetrating dating violence more often than did males but reported using milder forms, like slapping or hitting, instead of choking and punching," she said. "One limitation of the study is we don't know if this was in response to a sexual advance or some other type of (unwanted) behavior." The study also found that siblings closer in age experienced greater levels of violence than those spaced farther apart, probably because they spend more time together at home and school and are more likely to travel in the same social circles, Noland said.
No differences were found based on race or whether children had grown up in broken homes.
Doniece Sandoval, director of communications for the San Francisco-based Family Violence Prevention Fund, a national nonprofit organization dedicated to ending violence against women and children, called research such as Noland's work on sibling violence "critical."
"Studies have found that school-age children who witness or experience violence exhibit a range of problem behaviors, including depression, anxiety and violence towards peers," she said. "When they grow up, these children are also more likely to become batterers as adults. When violence occurs between siblings and parents don't intervene or tell their children that the behavior is inappropriate, children come away with the message that violence is an acceptable behavior."
Unlike other forms of family violence, sibling squabbles are often considered harmless, but it can have long-term consequences, Noland said. People who have suffered very contentious sibling relationships often have problems with self-esteem and relationships later on, she said.
"It doesn't take an injury to create a problem," she said. "A brother who tells a sister day in and day out that she's fat and ugly can do a lot of damage." Sibling violence makes childhood the ideal time to intervene with anger-management techniques that teach violence is not acceptable, Noland said.
"Our siblings are our first friends," she said. "We learn so much from them."