Step 1 : Introduction to the question "How are Teddy Roosevelt and FDR related?"
...Theodore Roosevelt Jr. was an American statesman, author, explorer, soldier, and naturalist, who served as the 26th President of the United States from 1901 to 1909. He also served as the 25th Vice President of the United States from March to September 1901 and as the 33rd Governor of New York from 1899 to 1900. As a leader of the Republican Party during this time, he became a driving force for the Progressive Era in the United States in the early 20th century. His face is depicted on Mount Rushmore, alongside those of George Washington, Thomas Jefferson, and Abraham Lincoln..
Step 2 : Answer to the question "How are Teddy Roosevelt and FDR related?"
FDR was Teddy's 5th cousin:
While many Americans may assume that President Franklin D. Roosevelt (1933-1945) was the son of Theodore Roosevelt (1901-1909), the two former presidents who led the country three decades apart were actually fifth cousins. Their closest tie was FDR’s wife Eleanor who was also the niece of President Theodore Roosevelt. Uncle Teddy was president of the United States in 1905 and even walked his brother Elliot’s daughter down the aisle. (And yes, that means the president and first lady were fifth cousins once removed.)