A five-year study commissioned by the nation’s Roman Catholic bishops to provide a definitive answer to what caused the church’s sexual abuse crisis has concluded that neither the all-male celibate priesthood nor homosexuality were to blame.

Instead, the report says, the abuse occurred because priests who were poorly prepared and monitored, and were under stress, landed amid the social and sexual turmoil of the 1960s and ’70s.

Known occurrences of sexual abuse of minors by priests rose sharply during those decades, the report found, and the problem grew worse when the church’s hierarchy responded by showing more care for the perpetrators than the victims.

The “blame Woodstock” explanation has been floated by bishops since the church was engulfed by scandal in the United States in 2002 and by Pope Benedict XVI after it erupted in Europe in 2010....