Section 415. Duties to support recipient of public assistance or welfare and patients in institutions in the department of mental hygiene

Except as
  otherwise provided by law, the spouse or parent of a recipient of public
  assistance or care or of a person liable to become in need thereof or of
  a patient in an institution in the department of mental hygiene,  if  of
  sufficient  ability,  is  responsible  for the support of such person or
  patient, provided that a  parent  shall  be  responsible  only  for  the
  support  of  his  child  or  children  who  have not attained the age of
  twenty-one years. In its discretion, the  court  may  require  any  such
  person  to  contribute a fair and reasonable sum for the support of such
  relative and may apportion the costs of such support among such  persons
  as  may  be  just and appropriate in view of the needs of the petitioner
  and the other circumstances of the  case  and  their  respective  means.
  Step-parents  shall  in  like  manner  be responsible for the support of
  children under the age of twenty-one years.