From Cinderella to Cordelia: Tales of Wicked Elder Children

Going through some Sufi Teaching Stories the other day, I am once again struck by the marked preference for the youngest child. 

Have you noticed how in folk tales and old stories, the youngest is usually the truest, the bravest, the purest, the nicest one who will brave persecution and fire-breathing dragons and unkindness and will win the prince or the princess or the kingdom or the treasure or whatever in the end (with supernatural elements always coming to his/her aid), while the eldest, or the first two children, are wicked and greedy and come to a Very Bad End? All the way from Cinderella to Cordelia (King Lear, Shakespeare), mind you. 

And this is not restricted to any culture - I have come across this in folk tales and stories from across the world - India, Tibet, Africa, France, Norway, South America, Russia, Canada, China, and Red Indian myths to name a few that I remember - practically all cultures seem to share this belief, irrespective of geographic location. WHY? 

 Have asked this question to many learned people from various places during my university teaching days. Everyone had further proof to add to the observation from their own or other cultures, but no one seemed to know WHY, no one seemed to know of any research already done on this. 

Assuming that writers by and large draw on reality, is it because parents get better at parenting and more relaxed after each child - so while the eldest has to survive all trial-and-error parenting, the youngest is brought up with fewer struggles, with tested methods, and turns out better balanced? Or is it that the youngest is likely to be more pampered more often than not, and is therefore more self-assured? Or is there any genetic reason behind this? Or are the writers not basing themselves on reality, but simply cashing in on the softer feeling we naturally have towards young ones? Or was it a simple narrative constraint - that to contrast the good with the bad, you had to start with bad, so start from the top of the sibling line? (Notice that the comparison is usually between siblings of the same gender) Or have I missed some point that is so obvious I had to miss it? (!) 

But then if an elder child grows up on stories where the younger one is always better, won’t it condition their growing mind even though they are not aware of the damage? Like years later they may realize that they didn’t fight too hard against a blatant unfairness because they somehow felt it was the way things should be, that it was somehow “right” and they didn’t deserve anything better? 

 Aren't these “somehow”s impressions that have been sneaked into our psyche surreptitiously, isn’t it subliminal perception or whatever? So do these stories cause damage? And how much? 

 Wicked Elder Child Theory. 2004.