The little lady her team studied was definitely an exception to the rule: she carried three genomes, making her a "triploid" organism. Analysis of her DNA revealed that most of the genes taken from males of other species—Ambystoma laterale, Ambystoma texanum, and Ambystoma tigrinum—had been expressed equally. Genes make us who we are by instructing our cells to make certain proteins at certain times, contributing to specific bodily structures and processes. We say a gene is "expressed" when it's allowed to do the thing it's meant to do, leading to some physical result. If you've got multiple genomes kicking around, you probably have genes that don't need to be turned on—they might be duplicates of a gene from another source, or even produce proteins that conflict with those made by different genes. According to the new study, while a salamander seems to pass her ill-begotten genes down in all manner of assorted mixtures, her daughter is likely to use the resulting genomes pretty equally to dictate her bodily functions. That's unusual in the world of hybrids.