I see these results as possibly being skewed by a few common social issues. One, low testosterone may be associated with those that tend to be bullied or victimized a lot in life, and their seeming lack of generosity may be the result of not trusting others, and a higher dependence on ones own actions to survive. The other, high narcissicism and testosterone may be associated with being possibly more successful financially, and the use of charity for tax write-offs. It just doesn't make any sense that a narcissist would be charitable without outside influences for being that way, unless they view themselves as some humanistic saviour.