This is what the suttas say about the three types of streamwinners you have mentioned above (ekabiji, kolamkolo, sattakkhattuparamo), for example at AN9.12 (quotes from Bhikkhu Bodhi):
… With the utter destruction of three fetters, this person is a one-seed attainer who, after being reborn once more as a human being, makes an end of suffering.
… With the utter destruction of three fetters, this person is a family-to-family attainer who, after roaming and wandering on among good families two or three times, makes an end of suffering.
…With the utter destruction of three fetters, this person is a seven times-at-most attainer who, after roaming and wandering on among devas and humans seven times at most, makes an end of suffering. …
I heard a story that there are occasionally “special” children in Thailand who are drawn to monastics and enjoy meditation at a very early age. Anyway, folklore and mainstream beliefs can be very misleading, so I wouldn’t consider that reliable evidence.
I know someone who had a very strong sense of recognition when she came in contact with the Dhamma, and she has very strong practice.