Tolumnia with double spike

Tolumnia with double spike

 

                    Is the rare double spike on Tolumnia genetic or culture?

                    I've found 5-6 plants that have two flower spikes on the same fan.  That's 5-6 out of 11,000 plants.  If it is genetic, we need to select for this trait.  If it's just good growing health of the plant, we should learn how to do that.

                    If anybody out there knows the answer, please tell me.