Mother Devki had given birth to the Lord Krishna but due to unavoidable circumstances Mother Yahoda had brought up Krishna as her son.So who among the two was actual mother of Lord Krishna,one who had simply given birth to God Krishna or one who brought up God Krishna like his mother?
Actually love does not know any discrimination/differentiation.Who ever loves us like our own mother we must regard/pay respect to her like our own mother,even if she had given birth to us or not.
This stands for our sisters also.By birth one may not be our sister but if one loves us or likes us as our sister we must love her like our own sister without discrimination.