Thanks to Kristen @ E! for the following Heroes spoilers.
According to her, seems like Claire is not the only character on the show who is adopted. About the adoption case scoop, Kristen has this to say "And the next adoption twist is perhaps my favorite twist ever on this show. You know how sometimes those silly promo guys say things like "It will change everything?" Well this one actually will."
Also, she shares that Monica will definitely be back as will Nana Dawson played by legendary Nichelle Nichols. As for West (played by Nicholas D'Agosto) she has this to say "I couldn't swear to it in a court of law, but I'm fairly sure he's gone, at least for the time being."
I'm hoping its Peter who was adopted, then there'll be some possibility of him and Claire having some on-screen romance! Anyway, till then.