A genetic cause for nonsyndromic primary VUR has been sought for about seven decades and we are still only part of the way there, though much has been done. This chapter begins with an explanation of why the study of VUR genetics is difficult. This is followed by descriptions of the different methods of searching for the answers, what we can learn from each, and some of the results that each has brought. It covers observations of inheritance patterns in families, genetic linkage and association, studies of optically visible chromosomal defects and methods of detecting chromosomal defects or rearrangements too small to see with the light microscope, and mention of haplotypes. We have learnt that there are many genes in which some variants can cause nonsyndromic VUR, and that they can be dominant or recessive, and autosomal or X-linked, but the majority autosomal dominant. There are millions of genomic differences between individuals throughout the genome. Brief descriptions are given of some of the databases and prediction methods used to determine whether a particular gene might be relevant and whether any particular genetic variant might be pathogenic, and accounts are given of some of the DNA sequencing studies and their yields.