No matter how endearing the motley cast of ABC’s Modern Family, new evidence shows the importance of “traditional family values”—or at least the presence of a father—in the cognitive development of a child.

Or maybe the television baby raised by the show’s gay couple would benefit from not one but two fathers, perhaps compensating for the lack of a mother? Regardless, investigators from the Research Institute of the McGill University Health Centre show that fraternal absence leads to impaired social and behavioral abilities in adults.

In experiments using mice, Gabriella Gobbi, an associate medical professor, says her team provided a fairly close analogue to the human species. "Although we used mice, the findings are extremely relevant to humans," she said in a statement. "We used California mice which, like in some human populations, are monogamous and raise their offspring together."

Gobbi’s colleague, Francis Bambico, likewise defended conclusions extrapolating results from the mouse model to humans. "Because we can control their environment, we can equalize factors that differ between them," he said. "Mice studies in the laboratory may therefore be clearer to interpret than human ones, where it is impossible to control all the influences during development."

The investigators compared the social behavior and brain structure of mice raised by both parents to those raised by “single mothers.” Among findings, mice raised without a father engaged in “abnormal” social interactions with more aggression than others, an effect stronger in female offspring. Interestingly, females raised without a father also exhibited greater sensitivity to the stimulant amphetamine, Gobbi said.

"The behavioral deficits we observed are consistent with human studies of children raised without a father," she added "These children have been shown to have an increased risk for deviant behavior and in particular, girls have been shown to be at risk for substance abuse. This suggests that these mice are a good model for understanding how these effects arise in humans."

More specifically, investigators identified neurological “defects” in the prefrontal cortex of male mice raised without fathers—the first such evidence that paternal presence affects the neurobiological development of offspring. Gobbi and her colleagues said they hoped other scientists would delve more deeply into the importance of parents—mothers and fathers—in a child’s neurodevelopment.

Similarly, findings by neurologists at the University of Pennsylvania announced in June showed that stressful life experiences in a father’s life effected epigenetic change to future offspring, reprogramming the later development of the hypothalamic-pituitary-adrenal axis, a region of the brain governing responses to stress. Such dysfunction of the stress response in some cases rises to the threshold of neuropsychiatric disease—highlighting the importance of a father, for better or worse.

Today, one-third of American children--some 15 million--are growing up in single-parent households mostly run by women, according to the U.S. Census Bureau's 2010 survey.

Source: Gobbi, Gabriella, Hattan, Patrick R., Lacoste, Baptiste, Bambico, Francis R. Father Absence In The Monogamous California Mouse Impairs Social Behavior And Modifies Dopamine And Glutamate Synapses In The Medial Prefrontal Cortex. Cerebral Cortex. 2013.