2. Usually has some degree of rebel in them; mostly in the wrong when in altercation with first sibling.
3. Willing to fight to the death over petty things to show parents that first sibling is in the wrong.
4. The cure for this syndrome is when the First sibling leaves the household, therefor leaving parents to become attached to Second sibling, until First sibling returns to home for a short stay(s).
Mark: "Mom, I would never do said thing, you know that, don't you"
Mom: "Of course hunny, I can not believe I am even questioning your integrity."
Mark: " Thank you, Joe is just going suffering from Second sibling syndrome."