The DRD4 gene is located on chromosome 11. We inherit two copies of the gene one from the mother and one from the father. Based on the repeat sizes there are 10 different genetic versions of DRD4. They range from two repeats (2R) to 11-repeats (11R).
In most studies individuals with 6 or fewer repeats are grouped together described as 4R and individuals with more than 7-repeats are grouped and described 7R. Inheriting the genetically changed versions with more than seven repeats (+7R), which includes 7R, 8R, 9R, 10R and 11R, are associated with increased promiscuity and increased numbers of extra-pair partners.