The Answer:

Only four of this country's presidents can be considered only children.

Franklin D. Roosevelt

Gerald Ford

Bill Clinton

Barack Obama

All four had half siblings, however. Roosevelt had a younger half brother. Ford had four half brothers and two half sisters. Clinton has one younger half brother. And Obama has a half sister.

Interestingly, 11 U.S. presidents were the oldest child in their family, and six presidents were the youngest child in their family.

—The Editors