Turnip Facts

Like rutabaga, turnip contains bitter cyanoglucosides that release small amounts of cyanide. Sensitivity to the bitterness of these cyanoglucosides is controlled by a paired gene. Subjects who have inherited two copies of the sensitive gene find turnips twice as bitter as those who have two insensitive genes, and thus may find turnips and other cyanoglucoside-containing foods intolerably bitter.
-Wikipedia