Described are methods to select animals, such as mammals, particularly domestic animals, breeding animals or animals destined for slaughter, for having desired genotypic or potential phenotypic properties, in particular, related to muscle mass and/or fat deposition lean meat, lean back fat, sow prolificacy and/or sow longevity. Provided is a method for selecting an animal having desired genotypic or potential phenotypic properties comprising testing the animal, a parent of the animal or its progeny for the presence of a nucleic acid modification affecting the activity of an evolutionary conserved CpG island, located in intron 3 of an IGF2 gene and/or for the presence of a nucleic acid modification affecting binding of a nuclear factor to an IGF2 gene.
