THEN AND NOW: How American families have changed since the early 1900s

• Average family size is decreasing, and middle children could be going extinct.
• More and more Americans are living in multigenerational households.
• Smartphones have changed the way families interact.

Family traditions, recipes, and heirlooms can be passed from generation to generation relatively unchanged. But families themselves have undergone many changes due to advancements in technology, economic factors, and societal shifts.

Here's how families have changed from the 1900s to today.

The divorce rate is decreasing.

INSIDER Data sourced figures from the Centers for Disease Control and Prevention and found that the divorce rate has been steadily decreasing since the mid-1980s. In 2017, the rate reached 2.9 divorces per 1,000 Americans with only 787,251 divorces total — the lowest it's been since 1968.

Data scientist Randal S. Olson writes that the only major spike in the divorce rate was after World War II, probably because of  "pre-WWII marriages coming to an abrupt end once the romance of wartime marriage wore off."

INSIDER's Kim Renfro reported that some sociologists say there could be a link between declining divorce rates and more people deciding to live together before marriage.

Same sex marriage is now legal nationwide, but LGBTQ+ families still experience discrimination.

Same-sex marriage became legal in all 50 states in 2015 with the Supreme Court case of Obergefell v. Hodges.

Public support for same-sex marriage has also grown over the past decade, according to the Pew Research Center. In 2007, most Americans (54%) opposed same-sex marriage. Ten years later, in 2017, more Americans supported it (62%) than opposed it (32%).

Even so, LGBTQ+ families still experience discrimination, such as a Catholic school in Kansas City, Kansas, rejecting the child of a same-sex couple.

Average family size is decreasing.

In 2017, there were about 60.3 births per 1,000 women ages 15 to 44— the lowest rate since the US started tracking birth rates in 1909, according to LiveScience.

A mother's age at the birth of her first child has been steadily increasing for decades. According to data from the Centers for Disease Control, in 1980, it was 22.7. In 2013, it was 26.

Experts think there are several reasons for the decline including economic factors such as rising education costs and the 2008 recession, better sex education, and women choosing to focus on their careers and start families later in life.