besetting
adjective
definition: constantly tormenting, troubling, or preoccupying, as a need, temptation, or sin.
example: She always had a besetting need to be first in everything; for her, all of life was a competition.
example: Her husband never wished to hurt her or the children, but gambling was his besetting sin.
Quotation:
“You ask a lot of questions, don’t you?”
“My brother always says curiosity is my besetting sin.” (Cassandra Clare, Clockwork Angel)