The article mentions XX and XY as differentiating sex, but rejects it because "some individuals" aren't XX or XY. I would think those numbers are vanishingly s

The article mentions XX and XY as differentiating sex, but rejects it because "some individuals" aren't XX or XY. I would think those numbers are vanishingly small enough that for athletic categorization it would work well enough. And for the few that don't then you add another criteria.