[birg]

In 1981, he won his first big international role, as Damien Thorn, son of the devil, in Omen III: The Final Conflict___

[PallMal]

Either on-set or thereafter when filming Damien Omen III, he and the co-star Lisa Harrow met, hooked up and bore a son.

In other words, the one sex scene in that movie may have been real (or as close to real as can be).