JUSTIN BIEBER Baby DNA Test: Yeater's Ex-Boyfriend Says He's the Dad - Justin Bieber took a DNA test and now it's alleged baby mama Mariah Yeater's turn. As John Basedow (@JohnBasedow) reports, according to Mariah's attorney, baby Tristyn will be submitted for the test to compare his DNA to Justin Bieber's. Team Yeater, however, has a big problem with the DNA test the Biebs already took because no one representing Mariah's interests was present while it was administered. Not to be outdone, Mariah's ex-boyfriend, Robbie Powell, wants his own DNA test to prove he's the father. Powell has been approached by several media outlets to tell his story and he's currently reviewing his options.