i find the term "indigo children" to be such an abstraction, just like the term " third eye " ... to which an oversimplification might be ; " those with a spontaneous ( almost biological ) tendency to gain a bigger picture faster than others " ...and i feel an aura can turn indigo in the middle of one's life journey as well ... but only with the logic that the inherent tendencies were nurtured to be curbed and can "come out of the closet" at any point of life... Also , keeping with the generalisation that i have seen so far in life ; all shades of the spectrum exist... which also means that ones that change shades also exist !