They randomly chose 250 men with the name Sykes and asked for DNA samples: 61 replied with a swab from the inside of their cheek.

BBC: Surnames found in DNA

Run a swab down the inside of your cheek.

FORBES: All your genes are belong to us

You rub the inside of each cheek for one minute to get a good DNA sample, put the swabs into the plastic tube provided, sign a few forms and send it all back.

FORBES: Magazine Article

The samples could come from the personal items of the missing -- from toothbrushes and hairbrushes to used Kleenex or cigarette butts -- or by using a cotton swab to rub the inside of a survivor's cheek.

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