(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.