It's a differently-shifted/skewed normal distribution.
Human works well enough with no drink, a tot of rum might help fortify them slightly but a few more tots and they're Dungeoneering Under the Influence.
A dwarf has a scale that is almost up against "the maximum alcohol anyone could physically drink" (a limit like "you can't drinking negative amounts" that windows the otherwise function without spoiling the theoretical curve) and deteriorates as you head towards nothing.
Options for dwarf/human hybrid:
1) Peak efficienc set at average of parental peaks (stick to shandies?),
2) Random choice of which parent provides their tolerance/requirement,
3) Dominant gene (always Type 1, or 75% chance Type A, or whatever the genotype mixing and respective parent-races genomics dictates),
4) Epigenetics kicks in (which also suggests the possibility of Fetal Non-Alcohol Syndrome in pure-bred dwarves born into sufficiently 'dry' Fortresses),
5) As with the Liger (offspring of male Lion and female Tiger) creating a much larger animal than their Lion or Tiger half-siblings (or Tigon 'double-cross-cousins'), it could get weird, either in magnitude or direction, because "big, but not too big" development from one side is now just "big" or otherwise not traditionally constrained (i.e., if alcohol-focussing is caused by multiple genetic markers, then inheriting the dwarven need without the dwarven target of alcohol, it may pick up some alternative 'necessity' (from what is merely a 'predilectionv in the pure-human genome) like milk or... tea? Which there's a thread about, somewhere in this forum.)