Final answer:
John Aspinwall Roosevelt was Franklin D. Roosevelt's youngest son. He pursued a career in business and worked as an investment banker.
Step-by-step explanation:
The youngest son of Franklin D. Roosevelt was John Aspinwall Roosevelt. However, he was not as politically active as his older siblings. John pursued a career in business and worked as an investment banker. He was also involved in philanthropy and served on the board of various organizations.