In a study where participants rated the pleasantness of t-shirt odors, what gene alleles influenced their odor preference

Major histocompatibility complex are the gene alleles that influenced their odor preference.  

Major histocompatibility complex (MHC), are group of genes found in mammals. Major histocompatibility complex codes for proteins that are present on cells surfaces and assist the acquired immune system to recognize foreign molecules. The primary role of MHC molecules is to attach to antigens obtained from pathogens and show them on the cell surface for recognition by the suitable T-cells.