(a) Subject to Subsection (b), if a genetic testing specimen for good cause and under circumstances the court considers to be just is not available from a man who may be the father of a child, a court may order the following individuals to submit specimens for genetic testing:
(1) the parents of the man;
(2) any brothers or sisters of the man;
(3) any other children of the man and their mothers; and
(4) other relatives of the man necessary to complete genetic testing.
(b) A court may not render an order under this section unless the court finds that the need for genetic testing outweighs the legitimate interests of the individual sought to be tested.
Official text of the Texas Family Code as published by the Texas Legislative Council.