8 U.S.C. § 1101(b)(2) (2010) (Title 8—Chapter 12: Immigration and Nationality)
(b) As used in titles I and II [8 U.S.C. §§ 1101 et seq., 1151 et seq.]—
(2) The terms "parent," "father," or "mother" mean a parent, father, or mother only where the relationship exists by reason of any of the circumstances set forth in (1) above, except that, for purposes of paragraph (1)(F) (other than the second proviso therein) and paragraph (1)(G)(i) in the case of a child born out of wedlock described in paragraph (1)(D) (and not described in paragraph (1)(C)), the term "parent" does not include the natural father of the child if the father has disappeared or abandoned or deserted the child or if the father has in writing irrevocably released the child for emigration and adoption.