One of the major themes the Democrats are pushing in this fall’s election is “income inequality.” After citing statistics that show that the gap between rich and poor in America is greater than it has ever been, they argue that this is a problem that can only be solved by governmental action, such as changing the rules on union elections, raising the minimum wage and increasing taxes on the rich. These kinds of steps are now being taken in New York City by its new mayor.

Conservative economists respond with statistics that show that the gap is actually smaller than the Democrats claim. They also cite studies that show that the decline in union membership has not contributed to it, that raising the minimum wage would actually hurt the poor and that heavy tax increases would slow down the rate of economic growth, thus hurting the poor even more. The battle is being fought on the basis of whose statistics are right.

However, there is a statistic outside of the political debate that strongly suggests that the problem does not lend itself to any of the proposed solutions. It measures the rate of the increase in the percentage of single-parent families in America and tracks almost exactly with the growth of the income gap.

In 1965, Daniel Patrick Moynahan, then an assistant secretary of labor in the Johnson administration, wrote a paper titled, “The Negro Family: The Case for National Action.” His central point was that many African-Americans (Negros, as they were then called) were facing a grim economic future because roughly 25 percent of them were being born to women who were not married. The comparable rate among whites was 3 percent.

Moynahan’s work was labeled “racist” because any mention of any social differences between white and black families was considered a slur against the latter. While his comments and suggestions were thus largely ignored, his predictions of serious trouble came true. Today’s numbers make the ’60s look like the good old days.

The rate of out-of-wedlock births has grown to 70 percent for blacks, 30 percent for whites and over 50 percent for Hispanics. Couple that fact with America’s high divorce rate and it means that roughly 25 percent of America’s children now live in single-parent homes and around 33 percent of them do not live with their biological fathers.

Leave aside the psychological studies on the deleterious effects of these conditions on children — they are legion — and focus solely on the economic impact. Twenty percent of children raised in single-parent homes end up in long-term if not life-long poverty, as compared to 2 percent of those raised in two-parent homes. A Penn State sociologist says that 41 percent of the income inequality created since 1975 came as a result of the changed family structure. A study by the Brookings Institution supports that, saying that the current poverty rate would be 25 percent lower if America had the same kind of families it had just 35 years ago.

Research by Brookings researchers shows that children can be saved from poverty if they do the following four things: Finish high school, get a job, don’t have children until they get married, and then, get married. Those growing up in two-parent homes are those most likely to have mentors and role models that will confirm that.

Getting kids to stay in school and to stop producing children outside of marriage would not only help close the income gap but also solve a whole host of other problems. The statistical proof is clear: the traditional two-parent family is still the most basic building block of a just society.

Robert Bennett, former U.S. senator from Utah, is a part-time teacher, researcher and lecturer at the University of Utah’s Hinckley Institute of Politics.

Correction: This column has been modified to correct the affiliation of researchers whose work shows ways to stay out of poverty.