My 6-foot, 12-year-old tree has lots of figs on one of its half-dozen trunks; the rest have nary a fig bud.  any thoughts on why this might happen?  Can I do anything besides enjoy the figs from the one trunk?  I've tried trimming some trunks, while leaving others untouched, with no effects.  

Background -- In-ground Washington  DC, Zone 7b/8a.  From cutting from "Marseilles" sold at Monticello, although red-fleshed rather than white.  Afternoon sun only. Produced abundantly from multiple trunks for several years, then froze almost to ground in polar-vortex winters of 2013-14 and 2014-15. Recovered and grew quickly, but this is first year since then with significant production. Leaves and branches on all trunks similar, no obvious damage or other problems.