The number of A-list Hollywood couples who found love on film sets would seem to suggest that the chances of off-screen love for on-screen co-stars is higher than normal, or maybe we just hear about them.
It seems hours of sitting around - often in locations far away from the rest of humanity - with only each other for distraction and amusement has led to innumerable romantic unions being forged as the camera winds... which can be no good for the poor cuckolds left back home, in some notorious cases.
The other thing of note is how moderately successful many of the films turned out to be - Rachel Weisz and Daniel Craig's Dream House, anyone? - compared with the passion that was going on off-screen. Perhaps these besotted beauties had nothing left to give to their craft.
Here are some of the more celebrated couplings which got steamy on film sets - including a few that were as shocking and dramatic as anything that later appeared on the big screen...