A person’s eggs release chemicals after sex that preferentially attract sperm from certain people, which might help explain why some people have fertility problems
Source:
https://www.newscientist.com/article/2245679-human-eggs-release-chemicals-that-attract-some-sperm-more-than-others/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home