Over the last 100 years or so, there has been a large volume of research into the human 'disgust' response.
Although there are (slight) cultural differences across the world, it's currently regarded as a truly 'innate' (rather than learned) emotion - one which has fairly obvious evolutionary advantages. As an example, a 'disgust' response to rotting food may well save lives, and so people with this facility have the opportunity to pass on the trait to future generations.
There is currently no explanation as to how such behaviours can be biologically 'passed on'. As far as in known, the only route would be through DNA, and there's no theory about how it can code for behaviours.
Note: This is just one example of the numerous - and sometimes complex - behaviour patterns which are somehow inherited, by as-yet-unknown mechanisms.
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