in contrast, a paternal effect is when a phenotype results from the genotype of the father, rather than the genotype of the individual. the genes responsible for these effects are components of sperm that are involved in fertilization and early development. an example of a paternal-effect gene is the ms(3)sneaky in "drosophila". males with a mutant allele of this gene produce sperm that are able to fertilize an egg, but the sneaky-inseminated eggs do not develop normally. however, females with this mutation produce eggs that undergo normal development when fertilized.