The definition of family has changed in the decades since “Father Knows Best” was a popular TV show. Instead of Mom cooking and cleaning on the home front, Dad at work all day and then dispensing wise and dispassionate justice when he came home in the evening, families can be single parents, same-sex parents, children from previous marriages blended in a new union and even multi-generational households. And if there are two parents, both likely work.

While the definition has broadened, the importance of the family as a social building block remains critical.

Britain’s Prime Minister David Cameron, in speaking to Parliament, about the youthful rioting in his nation, accurately identified part of the problem. Crime has a context and part of that context is that children are “growing up not knowing the difference between right and wrong,” he said.

“In too many cases, the parents of these children — if they are still around — don’t care where their children are or who they are with, let alone what they are doing,” he said. “The potential consequences of neglect and immorality on this scale have been clear for too long, without enough action being taken.”

A recent study, commissioned in the United Kingdom, coincidentally, shows what many people already knew: an engaged father makes his children better. Specifically, the study showed that fathers spending time with their children resulted in smarter kids.

The differences in intelligence between those with strong father relationships and those without were detectable even when the offspring were 42 years old, the study found. Not only did children with engaged fathers have higher IQs, but they also had more success in their jobs.

A report on the research project published by the London newspaper The Telegraph quoted researcher Dr. Daniel Nettle who directed the study: “What was surprising about this research was the real sizeable difference in the progress of children who benefited from paternal interest and how 30 years later, people whose dads were involved are more upwardly mobile. The data suggest that having a second adult involved during childhood produces benefits in terms of skills and abilities that endure throughout adult life,” he said.

The research, which studied more than 11,000 British men and women born in 1958, revealed that it was not enough to have a two-parent household; the father had to be actively involved for the positive impact to be recorded. The researchers asked mothers to what degree the father was available for “quality time” interaction with the child or children, including reading to them and organizing outings.

Such studies confirm the importance of functioning families and the value of the two gender role models. Such studies can and should have an impact on public policy.

As Mr. Cameron said, “We need a benefit system that rewards work and that is on the side of families. We need more discipline in our schools. We need action to deal with the most disruptive families.”

Those ideas are neither liberal nor conservative; they are sensible.