true facts. the pill confuses biology.

The introduction of the pill could be touted as the creator of modern sexuality. But it could also be responsible for confusing hormones and attracting ill-suited partners, new studies say.

The British study confirms past ideas that a woman's taste in men is skewed while on the pill - in the wrong direction. The pill alters the type of male scent that women find most attractive to those who are less genetically compatible.

To take this the Rachel Paiste step further: perhaps this is one of the reasons why the divorce rate went up with the regular use of oral contraceptives.

When not under the influence of extra estrogen, women are attracted to the pit stains of dudes that have incredible different genetic structure than themselves.
However, when on the pill, women chose those with a genetic build similar to their own, exponentially raising the possibility of mutation and immune weaknesses. It is not normal to be attracted to someone genetically close to you.

the technical part: Several previous studies have suggested that women tend to prefer the smell of men who are different from them in a cluster of genes called the major histocompatibility complex (MHC), which governs the immune system. Some of these studies have also found that this effect is not seen among Pill users. [famous t-shirt tests]

Unlike some previous studies, this research did not find any preference for dissimilar MHC genes. However, when the women started taking the Pill their preferences shifted towards the scent of men with more similar genes to their own.

This suggests that Pill use has an effect on perceptions of scent attractiveness, even if there is no underlying female preference for similar or dissimilar MHC genes.