I wonder what the medical reason for that is, but I think it has something to do with confidence and self-belief with the testosterone. They just, I think that's a big part of it.

When a female takes testosterone, the profound and permanent effects of the hormones can be seen in a matter of months. The voice drops, beards sprout, body fat is redistributed, sexual interest explodes, aggression increases, and moods can be unpredictable.