⇒⇒⇒a favoritism between two sister can influenced their psychological aspects for instance, a young sister is more partiality than her older sister,  the older sister feel that she's not worthy not commendable she feel lower than somebody's usual standards of behavior, and her sister is more valuable than her. but some should be realize that,  it is inequitable for them, as a  parents should be understand , their right is to  treat them balanced. its very unfair. being a favoritism is humiliation it can damages prides and dignity. perhaps their parents are damaging ego.....