(a) Testimony.--The court shall hear testimony in support of the petition and such additional testimony as it deems necessary to inform it as to the desirability of the proposed adoption. It shall require a disclosure of all moneys and consideration paid or to be paid to any person or institution in connection with the adoption.

(b) Investigation.--The court may request that an investigation be made by a person or public agency or, with its consent, a voluntary agency, specifically designated by the court to verify the statements of the petition and such other facts that will give the court full knowledge of the desirability of the proposed adoption, or the court may rely in whole or in part upon a report earlier made under section 2535 (relating to investigation). In any case, the age, sex, health, social and economic status or racial, ethnic or religious background of the child or adopting parents shall not preclude an adoption but the court shall decide its desirability on the basis of the physical, mental and emotional needs and welfare of the child.

(c) Payment of investigation costs.--The court may establish a procedure for the payment of investigation costs by the petitioners or by such other persons as the court may direct.