Fear of falling in love or being in love.
'Evolutionary' psychologists point to data that suggests that there is indeed a familial, and hence, possibly, a genetic tendency for at least some phobic fears. They also believe that the clustering of phobic fears around certain stimuli (i.e. the non-random distribution) itself invites an adaptationist explanation. They suggest that even though phobias are concerned with seemingly irrational fears, they can be, at least partly, accounted for by evolutionary models and theories.