Meaning: someone or something that is a bad influence or produces bad results (definition).


Example: Always getting into mischief, the youth was the bad seed of a troubled family.

Origins: Biblical references to the effect of sewing seed in fields. (Source.)


Rewrites:

a flawed seed a wayward seed a seed of no good character a withered planting a pit with no future a fruitless fount an ill-gained grain an unproductive kernel a profitless pip
Discussion: Some definitions prescribe a genetic element as the source of poor production, but the usage I’m familiar with makes no such association, unless it’s simply understood.