The major histocompatibility complex (MHC) of immunity genes has been reported to influence mate choice in vertebrates. and a recent study presented genetic evidence for this effect in humans. Specifically. greater dissimilarity at the MHC locus was reported for European-American mates (parents in HapMap Phase 2 trios) than for non-mates. https://www.jandroutboard.com/product-category/tracer-pellets/