MIB may have influenced people before the initial plane crash just like Jacob did. The reason for this is, I just rewatched season 5 a sayid centric episode (after namaste). Just after young sayid killed the chicken, he is touched by his father and then you hear the MIB chuckle sounds for a brief moment.
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Ilana who is obviously touched by Jacob (she knows most on the topic) and wants to kill Sayid off the island