The Genes For Love A Part Of The Major Histocompatibility Complex
Scientifically speaking "Romantic Chemistry" is determined the Major Histocompatibility Complex (MHC) a group of proteins that pepper the surface of your cells that help your immune system to recognize and fight pathogens. The MHC genes are also know to influence our mate-choice, where variations in the DNA code of MHC class I genes are known to influence our partner choice. The many sweaty t-shirt experiments really demonstrated that MHC influences both body scent and body scent preferences in humans (Wedekind et al., 1995 ,...etc...Kromer et al., 2016), people with very different MHC genes will tend to have find each others scent pleasant, while people with similar MHC genes find each other's scent repulsive.
A study in an Asian American population has found the MHC-based attraction AKA "Romantic Chemistry" is just as important as personality in predicting second date offers (Wu et al., 2018). MHC genes also play a role partner choice in other vertebrates, an interesting study in obligate pair-living lemurs showed that couples with mismatched MHC genes tend to make an extra-pair partner selection the cause of lemur affairs (Schwensow et al., 2008). MHC compatibility is so important that scientists have proposed humans invented kissing as a way to test for chemistry and this biological phenomenon can even help explain the strength of the female orgasm (Sherlock et al., 2016).
In real life, your sense of smell is a natural radar to detect romantic chemistry and assist with partner choice in-person, so a good place to meet a prospective partner is actually your local gym. If you prefer to use an online dating app try "DNA Romance" we are a genetic matchmaking site that use information hidden in your MHC genes to predict romantic chemistry between you and your match online. DNA Romance is easy to use just upload your raw autosomal DNA data file, within 30min your matches are ready!