Thomas Jefferson, 3rd President of the United States of America is George Washington, 1st President of the United States' second cousin once removed's wife's brother!

George Washington, 1st President of the United States
 

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Augustine Washington, Sr.
his father

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Mildred Gale
his mother

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Elizabeth Lewis
her sister

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Col. Charles Lewis of "Byrd"
her son

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Charles Lewis, of Buck Island
his son

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Colonel Charles Lilburn Lewis, Jr.
his son

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Lucy Lewis
his wife

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Thomas Jefferson, 3rd President of the United States of America
her brother