Would it be self?

Westermarck effect works for most people, both for most fathers and for most daughters.

The corollary is that incestous attraction is most of times unrequited, because if Westermarck fails for one family member, it still is most likely to work for the target of the attraction.

For whom does Westermarck effect fail more often - fathers or daughters?

Obviously self-control does not work if it is not self who has the attraction.

How would you control a daughter who in in your AoA, whom you love - and who loves you in a way contrary to Westermarck?