Although parents may love their children equally, natural preferences still enter into the human heart. Feelings are not sins, but that does not relieve us of the responsibility to act fairly. When favoritism dominates family relationships, polarizations and divisions can occur.
Quote by S. Padre Pio:
Let us live a lively faith, a firm hope, and, an ardent love, with eyes fixed on heaven and the keenest desire as long as we are travelers, to dwell one day in heaven whenever this is pleasing to God.