The families told reporters they had no idea why their DNA samples were collected and that the officials did not give them any reason either.
The 39 Indians, mostly from Punjab's Amritsar, Gurdaspur, Hoshiarpur, Kapurthala and Jalandhar districts, went missing in Iraq's Mosul when it was overrun by ISIS.
The central government continues to classify the 39 men as "missing".
External Affairs Minister Sushma Swaraj has on several occasions over the past three years assured the families that the government was making all efforts to trace the missing men.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)