Two forms of horror - rational and irrational - are described. The first of them is based upon logical comprehension of real danger, the latter - on inherited forms of behavior. Innate horror concerning primates combining human and animal features is its example. The hypothesis explaining it as a result of human forefathers' and representatives' of parallel branch of humanity conflicts is presented. The author's own observations and literary data suggest that some descendants of this branch can still exist but stay unrevealed because of psychological specificity of relations.