Principle on which questions relating to custody, upbringing, etc., of children are to be decided

Where in any proceeding before any court, questions (a) the custody or upbringing of a child; (b) the administration of any property belonging to or held on trust for a child, or the application of the income thereof, is in question, the court shall in deciding that question, regard the welfare of the child as the first and paramount consideration, and shall not take into consideration whether the claim of the father, in respect of such custody, upbringing, administration or application is superior to that of the mother, or vice-versa.