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