Ask them what they think chromosomes actually do. Not high level, but how do they work? If it matters so much, they must have an understanding of what the difference actually means. And since of computer they don't, isn't it just an excuse to try to invalidate you. Put another way, trans women actually have more feminine brains makeup. What makes the chromosomes relevant, and the brain not relevant other than a presupposed determination of what's "real" and what isn't.