We tend to assume that all genetic variation is good: the higher the variation in a population, the more diverse its gene pool, the more secure its future. Unfortunately, the relationship between genetic variation and survival of a population or a species is more complex. Some genetic variants are advantageous, increasing the survival and reproductive output of an individual, while others may be neutral now (but potentially advantageous in the future), and finally, some genetic variants are disadvantageous. All organisms carry a burden of disadvantageous genetic variants, called 'genetic load'. This genetic load can lead to diseases or morphological abnormalities and reduce survival or reproduction. Although genetic load has been studied for decades, recent technological advances now enable a more detailed understanding of its characteristics and potential consequences in wild species.