Eye color and sense of humor can run in a family. So can crime.
The killings of two adolescent Oregon girls may be the latest example of how different generations in a family can make the same terrible decisions.
Ward Weaver III, 39, is the principal suspect in the deaths of Ashley Pond and Miranda Gaddis, whose bodies were found buried beneath a concrete slab and in a shed at Weaver's home. He is jailed on charges of raping his son's girlfriend, and has a past conviction for assault with a deadly weapon.
Weaver admitted on ABCNEWS' Good Morning America he had failed a lie detector test, but denied involvement in the crime. His son Francis told police Weaver had confessed to raping and killing the girls.
Weaver's Father on Death Row for Similar Crime
It is not the first time Weaver's family has been associated with murder and sexual crime.
"They're trying to make a 'father and son' connection here because my father has a severe history," Weaver told Good Morning America in July.
Weaver's father, Ward Weaver Jr., is on California's Death Row for killing a young couple in 1981. The bodies were found under a freshly poured concrete slab behind his home.
He had also served time for rape and confessed to beating to death Robert Radford, 18, and raping and strangling the man's fiancée, 23-year-old Barbara Levoy.
According to court records obtained by the Portland Oregonian, the elder Weaver buried Levoy's body, then moved the remains to a hole behind his home. He forced his son Rodney, then 10 years old, to help dig the grave and cover it with concrete.
Ward Weaver III has yet to be charged in the deaths of Gaddis and Pond earlier this year, but criminologists say it is not surprising that crime may run in the family.
"It's very clear that there's a strong relation between violent behavior in parents and violent behavior in children," said Alan Lipman, the director of the Center at Georgetown University for the Study of Violence.
Studies dating from the 1930s have shown a link between families' criminal histories and the likelihood of running afoul of the law, and data from the nation's federal prisons back this up.
Half of all juveniles in custody and 47 percent of state prison inmates have a close relative who has been incarcerated, according to the Bureau of Justice Statistics, a research division of the Justice Department.
The figures are no surprise to those involved in the justice system.
"A lot of times it seemed that no matter how hard you tried, if their parents were in prison, they would end there," said Kate Desmond, a supervisor with Oregon's Department of Community Justice who works with delinquent children.
"There are a couple families in Portland where I can say about half of them are in prison."
Patricia Baldwin, the county prosecutor in tiny Danville, Ind., says the same is true there.
"I think you definitely see it," she said. "We joke sometimes that people ought to get a family cell block."
Petty crimes and alcohol-related offenses seem the most common to run in families, which often show evidence of abusive relationships, Baldwin says.
"It's just like dysfunctional family raises dysfunctional children."
The Ramsey Family: 10 Brothers in Prison
The Weavers' case is far from the first time allegations of crime running in families have made headlines.
When Roy Ramsey was executed in Missouri three years ago, his family was familiar to law enforcement officials around the state.
Nine of his 10 brothers had served time, four of them for murder. One was killed after being released from prison.
Roy Ramsey, who was convicted of murdering a retired couple in 1998, blamed the crime on his brother Billy.
In Ohio in the mid-1990s, Jason Earl Wagner and his younger brother Troy were each convicted of attempted gross sexual imposition of preteen girls.
The men's father, Jeffrey Wagner, had been convicted of rape more than two decades earlier.
Rayful Edmond III and his mother, Constance "Bootsie" Perry were convicted in 1990 of running a major drug network in the District of Columbia. Edmond's father, sisters, brother-in-law, cousin and aunt were all eventually convicted of participating in the scheme.
Multiple-convict families have also reached the big screen. The recent movie City by the Sea tells the true story of a New York police officer whose father had been sentenced to death for murder and who's son was himself convicted of manslaughter.
Bad Environments Teach Bad Behavior
Thomas Blomberg, a criminology professor at Florida State University, says it is not hard to understand why crime runs in some families.
"Crime is learned," he said. "Not only do you learn how to carry out those behaviors, but also the rationalizations and justifications."
Children learn to see violence and criminal behavior as a solution to life's problems, says Lipman, the head of Georgetown's violence research center. Kids in these families also often receive less nurturing and are more impoverished than other families.
"Every family comes together in different ways. And crime is one way in which families can cope with frustration, desires, inability, [and] emotional strain," he said.
DNA May Be a Factor, Too
Some researchers believe there is a genetic predisposition to crime in some families.
"There are some classic twin and adoptive studies that show a link between biological parents and kids more than adoptive parents and kids," said Akers.
There is no evidence that some people are genetically destined to become criminals, however.
"At best, it's a kind of vulnerability," said Lipman, meaning that some children may be biologically less capable of controlling violent and anti-social urges.
Not Always Like Father, Like Son
Experts like Lipman and Blomberg emphasize, however, that most children grow up to be law-abiding citizens despite having family members who have committed crimes.
They also note that other factors can be used to predict criminal behavior, such as drug use and a teen's choice of friends.
"Family effect is less than peer effect in adolescents," said Ronald Akers, the director of the Center for Studies in Criminology and Law at the University of Florida.
Single parent families are slightly more likely to have children who commit crimes, he notes, and drug use in families is also correlated with increased chances of criminal behavior by offspring.
But given the complexity of human nature, it is not surprising that no one factor is an ironclad predictor of future problems.
"You're dealing with a vast variety of different behaviors," said Lipman. "You wouldn't expect a 'magic bullet' link."