Mihai Cartoaje schreef
A possible explanation of the lower quality of most hybrids is if bad
genes are recessive, so alleles (hope I'm using the word correctly) of
hybrids would contain two recessive bad genes.

Maybe the bad genes shall be weeded out by further selection.

+ + +
The other way about. A gene is a particular area of DNA with a certain
function. An allele is one of several possible variants of the gene, so
selection (natural or artificial) eliminates 'bad' alleles, not 'bad' genes.
You cannot select for genes, and if you manage to do so anyway there is a
fair chance you get a new species (as this would mean altering the scope of
the genome). BTW, it is very anthropocentric to speak of alleles being 'bad'
or 'good'. Mostly alleles just are, and are advantageous or not depending on
circumstance.

Of course, colloquially genes are referred to in the reverse of the true
situation. Hope this clarifies it,
PvR

If this is less than crystal clear, just use a book, any decent book!