Final answer:
The difference between sex influenced genes and genes that exhibit genomic imprinting is that the former are affected by the sex of the individual and often lead to sexual dimorphism due to hormonal influence, while the latter's expression is determined by parent-specific epigenetic imprinting, whereby only one parent's copy of the gene is active in the offspring.
Step-by-step explanation:
The difference between a sex influenced gene and a gene that exhibits genomic imprinting lies in how their expression is affected. Sex influenced genes are present in both sexes but are expressed differently depending on the sex of the individual. This is typically influenced by hormones and results in sexual dimorphism. For instance, male and female elephant seals exhibit different size and behavior due to sex-influenced genes. On the other hand, genes that exhibit genomic imprinting have their expression determined by the parent that contributed them; such genes are chemically marked or 'imprinted' during gamete formation, with the result that only the maternal or paternal copy of the gene is active in the offspring.
Genomic imprinting is an epigenetic process, where despite inheriting two copies of a gene - one from each parent, only one is turned on while the other is turned off or 'imprinted'. One of the most profound implications of genomic imprinting is observed through the study of diseases or disorders that are inherited in this parent-specific manner. Moreover, even identical twins with the same genomic information can exhibit different phenotypes, highlighting the significant influence of epigenetic mechanisms such as imprinting.