The short answer
There is no single licorice-aversion gene
Licorice preference is probably a blend of smell intensity, taste receptor variation, early exposure, and learned association. The most recognizable “licorice” signal in absinthe is usually trans-anethole, not licorice root itself.
For the Nowhere line, a person who dislikes licorice is often reacting most strongly to the anise–fennel axis: the same family of aromas that makes a bottle read instantly as absinthe.
Aroma route
Anethole reaches the nose first
Anethole is the sweet, anisic compound carried by green anise, fennel, and star anise. It is volatile, powerful, and strongly associated with licorice, fennel candy, and anise spirits.
A recent food-science review identifies variation in the olfactory receptor gene OR6C70 as associated with higher intensity perception of trans-anethole. That does not prove that OR6C70 determines whether someone likes licorice; it suggests one biological route by which the aroma can arrive louder.
Pimpinella anisum Foeniculum vulgare trans-Anethole OR6C70 gene
Taste route
Licorice root is sweet in an unusual way
Real licorice root contributes glycyrrhizin and related saponins. Glycyrrhizin can activate the sweet receptor complex TAS1R2/TAS1R3, but its sweetness does not feel like ordinary sugar. It arrives with a long, rooty, lingering finish that some people experience as medicinal or cloying.
That root sweetness is a different biological story from the anise aroma in absinthe. A person may dislike black licorice candy because of the aroma, the root sweetness, the bitterness, or all three.
Bitter route
Medicinal is a whole flavor category
Bitter perception is distributed across a family of TAS2R receptors, not one universal bitterness switch. TAS2R38 is the best-known example because of its relationship to PROP/PTC bitterness, but it is not established as the licorice-aversion receptor.
In the Nowhere palette, the medicinal impression can be reinforced by wormwood, hyssop, and the cool aromatic compounds in fenchone and thujone. This is why reducing anise alone may not remove a drinker's sense that a formula is “licorice-like.”
TAS2R38 gene Artemisia absinthium Hyssopus officinalis Fenchone Thujone