An '''affinity''' is a bonus to skillgain in a given [[skill]] or [[characteristic]].
Each character is created with one random affinity. Skills for which you have an affinity can be seen by an asterisk symbol (*) next to their name in the skills window. Note that if you have not unlocked that particular skill yet, by using it, it will not show up even if you have an affinity for it.
The effect on experience gain is 10% per affinity, stacking up to 5 times. It would be reasonable to assume that the maximum possible skillgain accrued from affinities (at the maximum stack) would be in the range of 50%.