5 CFR § 843.403
Proof of parentage
November 4, 2020
(a) A judicial determination of parentage conclusively establishes the paternity of a child.
(b) Except as provided in paragraph (a) of this section, a child born to the wife of a married person is presumed to be the child of the wife's husband. This presumption may be rebutted only by clear and convincing evidence that the husband is not the father of the child.
(c) When paternity is not established under paragraph (a) or (b) of this section, paternity is determined by a preponderance of the credible evidence as defined in §1201.56(c)(2) of this title.