This is the third in a series about 21st century families.

Q: What are the changes in 21st century families?

A: The information in this article is from the New York Times. The Times article is titled “The Changing American Family.” Researchers who study the evolution of the family are astonished at how fast the family has changed, often surpassing the predictions of these same researchers.

Andrew J. Cherlin, professor of public policy at Johns Hopkins University, states we now have complex families on a scale never seen before. However, Cherlin believes society and families still are undergoing changes and will continue to experience rapid changes.

Researchers who study survey, census and historical data, and conduct field studies of home life, have pinpointed important emerging themes. First, researchers, state families are becoming increasingly socially egalitarian, even though economic disparities widen. Families are more racially, ethnically, religiously diverse than even a half year ago.

Couples cross racial lines, religious differences, gender lines and political party lines. People not biologically related share medical directives, wills and legal adoptions. Single adults live alone and consider themselves a family of one.

Research shows adult singles are more apt than married couples to stay in contact with friends, siblings, parents and neighbors. This is the conclusion of Bella DePaulo, author of “Single Outs.”

Stephanie Coontz, social historian at Evergreen State College in Olympia, Washington, states there are not just more types of living arrangements and families today. Most people will move through different stages of living arrangements over their respective lifetimes.

The historical family of stable married parents living with their children is present in the educated elite but not in the population-at-large. Today, society is divided into haves and have-nots and I do’s and I do nots. Coontz states those in good marriages would not want any other living arrangement. But those persons who would benefit the most from stable marriages are those least likely to have resources to sustain stable marriages.

Americans continue to believe in the value of marriage and the family. Our society marries, divorces, remarries at rates faster than anywhere else in the world. Americans spend $70 billion on weddings a year. In an informal sample of 5 percent Americans with different ages, professions and hometowns, they were asked what came to mind first when they heard the word “family.” Answers were essentially the same: “Love. Kids. Mom. Dinner.”

In tracking the differences between past and present families, researchers start with the children. The national birthrate now is half of what it was in 1960. Fewer women are becoming mothers, and those who have children average two, compared with an average of three children in the 1990s.

A key reason for the decline in the birthrate is the cost of raising children. The Department of Agriculture says the average middle-class couple spends $241,080 to raise a child to 18 years. That figure does not include the cost of college or graduate school.

Not only has the fertility rate dropped but so has the rate of marriage, especially with young women, who do the majority of childbearing. Thus, 41 percent of babies are born out of wedlock, four times greater than the out-of-wedlock birthrate in 1970. This trend is not uniform demographically. Those women with a bachelor’s degrees or higher still adhere to the old standard of marriage before childbirth by 90 percent. With women who attended college but got no degree, 40 percent gave birth when they were unmarried. With women who have high school diplomas or less, 57 percent are unmarried when they have their first child.

More than 25 percent of these unwed mothers live with partners who might or might not be the child’s biological fathers. Another feature of the American family is the rising number of cohabiting couples. Between 1996 and 2012, cohabiting couples increased close to 170 percent, from 2.9 million to 7.8 million.

The birthrate for teenage girls has dropped by close to half since 1991, and by the turn of the century reached an all-time low. Public health attributes this phenomenon to improved sex education and birth control methods. The majority of unmarried mothers now are in their 20s and 30s.

Working mothers employed part- or full-time has quadrupled since the 1950s. Almost 75 percent of women with children at home work. Women who are the only or primary breadwinner has increased from 11 percent in 1960 to 40 percent.

Cultural attitudes are adapting to new family norms. Seventy-two percent of adults younger than 30, and 62 percent of the public, consider the ideal marriage as one in which men and women both work and then share child care and household duties.

Scholastically, most couples are evenly matched, but 28 percent of married women have more education than their spouses, whereas 19 percent of married men are better educated. Mothers with higher educations have increased competition for admission to elite universities. These desired universities stress extracurricular activities. The busyness of a child’s after-school activities is a predictor of the mother’s education level.

A surprising change in families is the recent decrease in the divorce rate. For several decades, the divorce rate hovered at approximately 50 percent. Since 1996, the divorce rate has dropped more and is now just above 40 percent for first marriages.

The decline in divorce is more pronounced in middle and upper-middle income couples who have college degrees. The expectation is one in three marriages will end in divorce. This prediction allows these couples to manage resources with confidence, and invest more in their children.

Among baby boomers, the marriage failure rate has increased to 50 percent in the last two decades. Divorce rates have not fallen for those who marry again and again.

• Next week’s article will be continuing with a discussion of changes in American families.

Judy Caprez is professor emeritus at Fort Hays State University.