check out the pedigree on Oliver Platt:

Platt was born in Windsor, Ontario, Canada, to American parents Sheila Maynard, a clinical social worker, and Nicholas Platt, a career diplomat who served as U.S. ambassador to Pakistan, Zambia, and the Philippines. His older brother, Adam Platt, is a New York magazine restaurant critic. They returned to the United States when Platt was three months old.

Platt's paternal great-grandfather was artist and architect Charles A. Platt, and his maternal great-grandparents were equestrian Arthur Scott Burden (of the industrialist Burden family) and socialite Cynthia Roche. Platt is also a great-great-grandson of General Robert Shaw Oliver (through his mother). He is a second cousin once removed of Diana, Princess of Wales, and of her brother Charles Spencer, 9th Earl Spencer, through his great-great-grandparents, MP James Roche and heiress Frances Ellen Work. When asked about Diana, Platt has said, "I never met her. It's a non-story. I'd love to tell you we were confidantes. The truth is I don't know much more about it than you do."

Platt's paternal great great-grandfather was diplomat and lawyer Joseph Hodges Choate. Choate was the most successful lawyer in New York City during the Gilded Age and was later appointed U.S. Ambassador to England by President William McKinley. His brother William Gardner Choate, who was also a prominent lawyer and federal judge, created Choate Rosemary Hall.