"Like father, like son." "It's in the blood." The intuition that criminality is inherited —that there are families, lineages and "bad seeds" destined for crime by their bloodline— is ancient and powerful. The theory of criminal heredity is the attempt to turn that intuition into science: the idea that the tendency toward crime is transmitted biologically from parents to children. It is one of the most influential and most dangerous theses in the history of criminology, because it brushes against a partial truth —children do resemble their parents— to leap to a false conclusion: that this resemblance proves that crime travels in the genes.
Criminal heredity at a glance
- Authors
- Richard Dugdale · Henry Goddard
- Era
- Crystallizes in the 19th c.
- Family
- Biological
- Idea
- The tendency toward crime is transmitted biologically from parents to children
Family resemblance in crime → attributed to the genes (confusing heredity with environment)// OriginThe Jukes, the Kallikaks and the dream of bad blood
The theory crystallized in the 19th century with the studies of criminal families. In 1877, Richard Dugdale published The Jukes, a tracing of an American family across generations abounding in criminals, beggars and "degenerates," concluding that degeneration was inherited. Decades later, Henry Goddard did the same with the "Kallikak" family. These studies, presented as proof of the heredity of crime, had enormous success and a devastating influence: they were the "scientific" basis of the eugenics movement, which proposed sterilizing the "genetically inferior" to prevent them from transmitting their supposed criminality. Thousands of people were forcibly sterilized in the United States and Europe on the basis of this logic.
Modern science refined the question with serious methods —the twin and adoption studies, which compare identical and fraternal twins, or children adopted by their biological and adoptive parents, to separate the genetic from the environmental—. And its answer was nuanced, not the one the eugenicists dreamed of: there does exist a certain heritability of traits associated with antisocial behavior (impulsivity, sensation-seeking), but "crime" is not inherited, and that predisposition is expressed only in interaction with the environment. The Jukes studies, moreover, were demolished: they conflated poverty with genetics, did not distinguish heredity from shared environment, and their data were, in large part, invented.
The resemblance that deceives
The heart of the problem is that family resemblance has many causes, and genetics is only one. When the child of a criminal is also a criminal, biological heredity is the least proven explanation of all: that child also inherited the poor neighborhood, the school that failed, the absence of opportunities, the direct learning of their parents' behavior, the stigma of the surname, the trauma. The "criminal dynasties" that seem to prove the heredity of crime actually prove that disadvantage is transmitted —through a thousand social channels, not just through the genes—. The theory of criminal heredity, in its naive version, commits the classic error of confusing correlation (criminals tend to have criminal children) with genetic heredity, ignoring that almost everything a parent transmits to a child —except the genes themselves— is also "inherited": the house, the class, the culture, the wounds. Separating those layers is the whole challenge.
The resemblance that deceives, step by step
- 1Real observationThe children of criminals do tend to offend more than average
- 2Naive leapThat resemblance is attributed to genetically inherited "bad blood"
- 3The underlying errorCorrelation is confused with heredity: the child also inherits neighborhood, poverty, learning and stigma
- 4What science actually showsTwin and adoption studies: moderate heritability of temperamental traits, not of "crime," and expressed only according to the environment
"Criminal dynasties" do not prove that crime is inherited: they prove that social disadvantage is transmitted through a thousand channels.
// In fictionFive dynasties of the blood
Fiction adores cursed lineages, and within them the question of heredity always beats. Illumi, from Hunter × Hunter, belongs to the Zoldycks, a family of professional assassins who have raised their children to kill for centuries —the perfect case for dismantling the theory, because their "gift" for crime is not genetic but a brutal training from the cradle—. el Barón, in Dune, embodies the aristocratic "house" whose depravity is presented as a trait of blood, transmitted from generation to generation like the title. And Tywin, the Lannister patriarch of Game of Thrones, lives obsessed with the family legacy: for him, blood and the surname are the only things that endure, and he molds his children —with monstrous results— to embody that inheritance.
The other two show the two faces of lineage. Bellatrix, in Harry Potter, is the fanatic of "blood purity" taken to a homicidal extreme: she literally believes that blood determines a person's worth —the ideology of criminal heredity turned into magical supremacism—. And Diosa de la Muerte, in Thor, is the hidden heir: the firstborn whose conquering violence Asgard concealed and denied, revealing that the "civilized" realm was founded on the same brutal blood she embodies. In all five, fiction poses the question the theory tries to answer: is the criminal born of their blood, or manufactured by their house?
From the caste of assassins to the hidden heir: five dynasties where blood seems destiny. Tap to open their case file.
// What we do knowHeritability is not destiny
The serious version of the question —is anything related to crime inherited?— has an honest answer worth pinning down so as to fall into neither denial nor determinism. Well-conducted twin and adoption studies show that certain temperamental traits associated with antisocial behavior have a moderate heritability: "stealing" or "killing" is not inherited, but in part impulsivity, low emotional reactivity or sensation-seeking are, and in certain environments they raise the risk. The key word is heritability, and it means far less than it sounds: it measures how much of the variation of a trait in a population is associated with genetic variation, not whether your destiny is written in your genes. And above all, that predisposition is expressed only in interaction with the environment —the lesson of the biosocial model and of the MAOA gene—: the same genes produce a delinquent or a surgeon depending on the life that surrounds them.
// The flawThe most dangerous alibi in criminology
The theory of criminal heredity is the one that has caused the most direct harm in the entire discipline, and its flaw is historical and bloody: it served as the foundation of eugenics. If crime is inherited, they reasoned, "born criminals" must be prevented from reproducing —and from there to forced sterilization, racial purity laws and, at its extreme, the Nazi extermination, there is a straight line—. This is no abstract concern: it is what actually happened, with tens of thousands of victims. That is why this theory demands the utmost ethical caution: any claim about the "heredity" of crime carries that shadow and can be used to justify controlling who has the right to exist. The second flaw is the individual alibi: "it's in my blood, I couldn't help it." Neither the heritability of a temperament nor a family surname forces anyone to offend —Illumi was trained to kill, he was not born knowing; and many children of criminals break the chain—. Blood is neither destiny nor excuse.
From the Jukes to forced sterilization
Few criminological ideas have had consequences so direct and devastating. The 19th-century "criminal family" studies were presented as proof that crime is inherited and became the "scientific" basis of the eugenics movement: if degeneration passes through the blood, the "inferior" had to be prevented from reproducing. Thousands of people were forcibly sterilized on that logic. Only modern genetics —twins and adoption— reformulated the question honestly, finding heritability of traits, not of destinies.
- 1877Dugdale publishes The Jukes: the degeneration of a family as proof of heredity (data later demolished).
- 1912Goddard publishes the study of the "Kallikak" family, with the same hereditary thesis.
- 1927The U.S. Supreme Court upholds forced sterilization (Buck v. Bell).
- 1984Mednick and others use adoption studies to finally separate the genetic from the environmental.
Lights and shadows
- It contains a grain of truth: behavioral genetics finds a moderate heritability of temperamental traits associated with antisocial behavior.
- It spurred rigorous methods —twin and adoption studies— that today allow the genetic to be separated from the environmental.
- It pointed out, clumsily, that biology matters: it prepared the ground for the biosocial model and gene-environment interaction.
- Its demolition taught how to distinguish correlation from heredity, a central methodological lesson.
- It confuses family resemblance with genetic heredity, ignoring the neighborhood, poverty, learning and stigma that are transmitted.
- Its founding studies (the Jukes) conflated poverty with genetics and contained invented data.
- It founded eugenics: it was the alibi for tens of thousands of forced sterilizations.
- It is used as a deterministic alibi —"it's in my blood"— that neither heritability nor a surname justifies.
// Why it mattersBreak the chain, don't blame the blood
Rightly understood, the theory of criminal heredity teaches exactly the opposite of what the eugenicists dreamed: that since the transmission of crime is above all social —poverty, learning, trauma, stigma passing from parents to children—, the chain can be broken by intervening in the environment, not in the genes. Programs that take a child out of a criminogenic setting, that give them the school, the support and the opportunities their family could not, achieve what no sterilization ever could: that the delinquent's child not become one. The "criminal dynasty" is not inherited like a biological curse; it is perpetuated as a social disadvantage, and for that very reason it is interruptible. Every Illumi raised to kill could have been something else with a different upbringing; that is the hope honest science offers against the fatalism of blood.
The theory leaves us a warning and a promise. The warning: always distrust anyone who says that crime "travels in the blood," because that idea has justified horrors and almost always hides a prejudice of class or race. The promise: that if what is transmitted is the environment and not a genetic destiny, then no lineage is condemned —and breaking the chain of disadvantage is possible, generation after generation—.
Three key takeaways
- Criminal heredity: the idea that crime is transmitted biologically from parents to children. It crystallized with studies of "criminal families" (Dugdale's Jukes) —later demolished for confusing poverty with genetics— and founded eugenics.
- The key error: confusing family resemblance with genetic heredity. Children inherit the house, the class, the neighborhood, the learning and the stigma as much as the genes. Serious science (twins/adoption) finds a moderate heritability of temperamental traits, not of "crime," and expressed only according to the environment.
- It is the theory that caused the most direct harm (forced sterilizations, eugenics, extermination). Its flaw is historical and ethical. But rightly understood it teaches the opposite of fatalism: since transmission is above all social, the chain is broken by intervening in the environment, not in the blood.
Sources · further reading
- Dugdale, R. L. (1877). The Jukes: A Study in Crime, Pauperism, Disease and Heredity. Putnam.
- Gould, S. J. (1981). La falsa medida del hombre. Norton.
- Mednick, S. A., Gabrielli, W. F. & Hutchings, B. (1984). «Genetic Influences in Criminal Convictions». Science, 224.
- Rafter, N. (1997). Creating Born Criminals. University of Illinois Press.