"P van Rijckevorsel" wrote
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.

Mihai Cartoaje schreef
I have researched in a biology book. Two genes might be alleles, or
they might not be alleles.

+ + +
No. You either have a bad book (not sure if they exist) or you read wrong.
Try a new book.
PvR