But also: People that I trained martial arts with, and I NEVER exchanged electronic messages with them, and I do not talk with them for 4 years now. Well, if y

But also: People that I trained martial arts with, and I NEVER exchanged electronic messages with them, and I do not talk with them for 4 years now. Well, if your instructor kept emails of all students in his personal address book, and he happened to share it with LinkedIn, then LinkedIn may deduce that each person on the list may be somehow connected to each other.