"P van Rijckevorsel" wrote in message ...

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

Solomon, Eldra Pearl, et al. Biology. 3rd edition. Sunders, Forth
Worth, 1993.

Page 233: "If genes occupy the same locus on each of a pair of
chromosomes, they are said to be alleles."

They use the expression "not allelic" otherwise. I understand "allele"
as "sister", except for genes.