The aim of the present study was to clarify the origins of the association between marriage and desistence from antisocial behavior using a population-based sample of male twins assessed up to four times between the ages of 17 and 29. Analyses offered support for both selection and causation explanations. Specifically, mean differences in antisocial behavior across married and unmarried men preceded the state of marriage by many years, and did so even when restricting the married sample to those who married at age 25 or later. Moreover, there was some evidence of selection in our co-twin control analyses, as the MZ between-pair and within-pair estimates could not be constrained to be equal. Such findings collectively point to an important role for selection processes, whereby men who eventually married were less prone to antisocial behavior during adolescence and emerging adulthood than were men who remain unmarried at age 29. However, visual inspection of the mean differences was also consistent with the possibility that entrance into the state of marriage may accentuate these pre-existing differences. These suspicions were borne out in our co-twin control analyses. At both ages 24 and 29, the within-pair effect of marriage on AAB was statistically significant for MZ twins. As MZ twins share all of their genes and early rearing environment, such results are indicative of a person-specific or non-shared environmentally mediated impact of marriage on desistence from AAB. That these results were equivalent to those in DZ twins, and moreover, persisted even when controlling for prior AAB, further bolstered our conclusion that marriage also serves to inhibit AAB. In short, the current results indicate that while men with lower levels of antisocial behavior are more likely to marry by age 29, entrance into the state of marriage accentuates their tendency to refrain from antisocial behavior.
Our findings are generally consistent with prior literature. Previous studies1–4
within the field of criminology have pointed to a causal effect of marriage on desistence from antisocial behavior. Perhaps the strongest such study found that the average reduction in crime with entry into marriage was approximately 35%2
. Our own results were very consistent with these findings. At age 29, the Cohen’s d
effect size for differences in AAB by marital status was .48, which corresponds to slightly more than a 30% reduction in AAB with marriage.
That said, our results also implicated the presence of selection processes, such that men who married by age 29 were less prone to antisocial behavior as adolescents than were their unmarried peers. Other studies, by contrast, have found little evidence in support of selection2, 3
. Although it is not clear what may account for this difference across studies, one possibility is clinical severity. Prior work has often examined high-risk/criminologic samples (such as delinquent boys who had been committed to reform schools during adolescence2, 3
), whereas the current sample was population-based. It may be that selection processes are more important (or are simply easier to detect) in population-based samples. Cohort effects are yet another, potentially more important, difference between samples. The current sample was born between 1972 and 1978, whereas the aforementioned high-risk sample2, 3
was born between 1924 and 1932. These cohort differences may be particularly salient in the current study given changes in the frequency and psychological meaning of marriage since the 1960s and 1970s25
. Indeed, the proportion of never married individuals has steadily increased since the 1970s as has the median age at first marriage26
. As marriage thus seems to be increasingly linked to individual choice rather than societal expectations, selection processes could simply be more influential in more recent decades. By contrast, there may have been little room for selection to exert a detectable effect in prior decades.
There are several limitations to bear in mind when interpreting the results of this study. First, only men were examined in the current study, as the link between marriage and desistence from antisocial behavior among women has been less consistently supported2, 27
. It thus remains unclear whether and how these findings might generalize to women. Building on this point, although we would expect assortative mating to operate in the choice of spouse (such that more antisocial men would marry more antisocial women28
), this process was not examined here as we do not have this information on the twin spouses. Moreover, we did not account for the possibility of psychiatric comorbidity, which may well act as a hindrance to desistence from AAB. Future researchers should seek to understand the role of assortative mating and psychiatric comorbidity in desistence from antisocial behavior.
The current results apply only to early adulthood and not to later developmental periods. This point is particularly salient since it is likely that many of the men who were unmarried as of their age 29 assessment will eventually marry17
. However, because antisocial behavior is more common in early adulthood than in later developmental periods29, 30
, early adulthood is a critical time to investigate predictors of antisocial behavior. It is also unclear whether the effects identified here are specific to marriage or whether they extend to other committed romantic states (i.e., engagement or cohabitation). We would expect our findings to generalize beyond marriage, as the presumed mediators of these effects (e.g., social control) should generalize to other sorts of romantic bonds. That said, at least one study4
found that the marriage effect did not extend to cohabitation. Future work should examine this possibility.
Finally, although extensive evidence now suggests that child- and adolescent-onset antisocial behavior differ etiologically23
, data regarding early-onset “caseness” was not available for the present study. One possible complication of this is that, if adolescent-onset cases were more numerous in the married group, they may be driving the change observed in response to marriage. That said, evidence indicating that the state of marriage inhibits antisocial behavior has also been found in high-risk/criminologic samples likely to contain a large(r) number of life-course persistent individuals1–4
. In any case, future research should evaluate whether these findings vary by the age-of-onset of antisocial behavior.
In spite of these limitations, the current results provide an important constructive replication and extension of prior findings indicating that entrance into the state of marriage inhibits male antisocial behavior. Rather than resulting solely from misidentified selection processes, it appears that marriage represents a potent and at least partially environmentally mediated influence on desistence from antisocial behavior. As argued by prior scholars2
, however, it seems unlikely that the institution of marriage acts to inhibit men’s antisocial behavior directly
; rather, marriage is likely a marker for other more proximal and causal processes. For example, prior work has suggested that the quality of the marital bond may mediate this effect3
. Future work should seek to more exhaustively identify the mechanisms mediating the impact of marriage on antisocial behavior.
Despite this evidence of an environmentally mediated effect of marriage on desistence from antisocial behavior, however, our results also implicate a clear role for selection processes, whereby men less prone to antisocial behavior as adolescents are more likely to marry (at least by age 29). There are many possible explanations for such findings6
. It may be that less antisocial men simply make more attractive marital partners, and are thus more likely to be selected for
marriage. Alternately, it may be that marriage is a less attractive option for men who engage in higher levels of antisocial behaviors, and they are thus less likely to select into
marriage. The latter would be consistent with the theory of the active gene-environment correlation (in which individuals select into environments consistent with their genotype31, 32
), a well-known theory thought to underlie mate selection in general33
. Regardless, given that marriage also appears to facilitate desistence from antisocial behavior, future research should seek to distinguish between and better understand these selection processes.