Larry Birkhead -- The DNA Expert

Asking Larry Birkhead about Justin Bieber's recent paternity issues is just too perfect ... considering he was involved in one of the most famous DNA tests ever.

You'll remember ... Birkhead found out he was the father of Dannielynn, Anna Nicole Smith's daughter, after a drawn out paternity battle in the Bahamas in 2007 that involved Howard K. Stern and even Prince Frederic Von Anhalt.