Most Americans Have Three or More Siblings

How many brothers and sisters do Americans aged 18 or older have? The 2018 General Social Survey asks about siblings with the question, "How many brothers and sisters did you have? Please count those born alive but no longer living, as well as those alive now. Also include stepbrothers and stepsisters, and children adopted by your parents."

Number of siblings
None: 4%
One: 21%
Two: 21%
Three: 16%
Four: 10%
Five: 7%
Six: 6%
Seven: 5%
Eight: 3%
Nine: 2%
Ten or more: 4%

Among all Americans aged 18 or older, the 54 percent majority have (or had) three or more siblings. But there are differences by age. Among adults aged 50 or older, fully 61 percent have (or had) three or more siblings. Among adults under age 50, a smaller 49 percent have (or had) three or more siblings.

Source: Demo Memo analysis of the 2018 General Social Survey

Most Children Live with Siblings

Among the nation's 74 million children under age 18, more than three out of four (78 percent) live with siblings. Only 22 percent do not have one or more siblings at home, according to the Census Bureau's Survey of Income and Program Participation...

58% of children share their home only with biological/adopted siblings
11% of children share their home only with half/step siblings
  8% of children share their home with biological/adopted and half/step siblings
22% of children do not have siblings living with them

Source: Census Bureau, A Child's Day: Parental Interaction, School Engagement, and Extracurricular Activities: 2014

How Siblings Affect Time Use

Nearly 80 percent of children under age 18 live with siblings, according to the Census Bureau. But no one has examined how the presence of siblings affects what children do on an average day—until now. A study published in Demographic Research uses time diary data from the Panel Study of Income Dynamics' Child Development Supplement to compare the time use of children with and without siblings at home. This is important, say the study's authors, because "the sibling relationship is typically the longest-lasting family relationship in an individual's life." Here are some of the most important differences in time use between children with and without siblings in the home...

• Children without siblings spend more of their discretionary time engaged with no one else—16 hours per week versus 12 hours for children with siblings.
• Children without siblings spend more of their time engaged with parents and no one else—22 hours per week versus 6 hours for children with siblings.
• Children with siblings spend more time engaged with others but not their parents—27 hours per week versus 17 hours for children without siblings.
• Children with siblings spend more time engaged with parents and others at the same time—15 hours per week versus 5 hours for children without siblings. 

"Children with coresident siblings spend the majority of their discretionary time engaged in activities with their siblings, highlighting the important role that siblings can play in each other's lives," the researchers conclude.

Source: Demographic Research, Siblings and Children's Time Use in the United States