He is the son of actor Dan Blocker, famous for portraying Eric "Hoss" Cartwright on the NBC Western television series Bonanza from 1959 until his death on May 13 1972 from a pulmonary embolism when Dirk was 14 and Dolphia Lee Blocker (née Parker). His brother is producer David Blocker.
He has been married to Danielle Aubuchon since November 3, 1990.
- Like co-star Joel McKinnon Miller, he was only credited under ‘also starring’ on the end credits in Season One despite appearing in every episode. In Season Two they were promoted to main cast but the title sequence wasn’t altered to include them along with the rest of the main cast. They are however both credited as ‘starring’ in the opening credits that show immediately after the title sequence before the production credits are shown.