Without more information, I can just say that, in general, load-bearing walls typically (BUT NOT ALWAYS) are those that are parallel with the long direction of a room. That's done so that the ceiling joists span in the shortest possible direction for that room. That also means the non-load-bearing walls will be perpendicular to the room's long dimension. The only way to be sure is to access the attic, if possible, digging through the insulation to see for yourself which direction the ceiling joists run.
And to throw another curve at you and hubby, it's possible to remove part(s) of or even all of load-bearing walls. I've lost count of the ones I've either completely removed or partially removed over the years. Doing so safely requires the services of an engineer, and I had access to a very inexpensive one (me) for every wall I removed or modified. Support systems to replace load-bearing walls usually consist of steel or built-up timber headers, designed to support the dead and live loads formerly carried by the wall. I always supported my headers on steel columns (to minimize buckling), fitted with custom header support brackets and resting on concrete footings. I've usually embedded the columns in adjacent walls for a clean look, along with hiding the header in the attic above the ceiling (where it carries the ceiling and rafter loads by means of joist hangers). If your duplex is a two-story, the challenge becomes slightly more complicated but still not insurmountable.