When you watch a game of football, you always cheer for one of the two teams. Why? Because, you are either with team A or team B. In very very rare cases people watch football. In nearly all the cases football is subsided by team belongings.
Same goes for everything in life. You are either with one idea or the other. You are either with one party or the other. Family life is not much different as well. Your father or mother love all their children, but they always love one sibling more than the other. Their apparent love for all of their offsprings, is a self-deception, crafted under social effects and pressures. The objectivity of parental love vanishes like infatuation, the moment their favorite child, enters a conflict with the less appreciated child. Understanding the fact of unequal, parental love, suddenly makes unquestioned parental love a dogma. What is a dogma? Well, dogma is something that we never question, despite all its shortcomings. The word dogma is normally reserved for religious beliefs.