The question is facetious, but I presume readers are aware of the genuine issue that lies behind the question. If not, I will sum it up briefly: The Gospels of Matthew and Luke both provide genealogies for Jesus. They contradict one another in after David except for a brief convergence around Zerubbabel.
So why propose – even in jest – this solution to the two male parents of Joseph who were purportedly distant cousins of one another?
The reason is because this proposal is more straightforward, and fits what the texts say better, than those which have been proposed by conservatives trying to defend Biblical inerrancy by harmonizing the genealogies.
The most common ancient approach was to posit a series of Levirite marriages, so that a woman’s husband died without producing children, and the dead man’s brother married his widow in keeping with Jewish Law. The most common modern approach is less convoluted and simply ignores what the text says, pretending that one of the genealogies is Mary’s rather than Joseph’s.
It is certainly a much more straightforward (if indubitably anachronistic) to have Jacob and Heli be a gay couple who both provided sperm in order for a woman to conceive a child for them, and so either could be the father.
Why avoid this simpler solution? Simple: because the same ideology that drives them to force a resolution to the contradiction also drives them to not want to appeal to this particular explanation. And it is important to notice this, that what drives the attempts at harmonizations is a particular ideology, one that ultimately will eschew a simple solution for a more complex one in order to maintain conformity to that ideology. Because ultimately it is that ideology and the defense of it that matters most, and not the elimination of problems in the Bible for their own sake.
What is probably most interesting in this is its relevance to the Synoptic Problem. The three options are that Luke knew Matthew’s Gospel, that a genealogy like Matthew’s was in Q, or that both independently inserted genealogies. The last option seems too coincidental. The first seems problematic to me given how Luke diverges so substantially from Matthew, especially in the infancy stories, although I am open to being persuaded. The Q hypothesis has rarely made a genealogy part of that source. Are there other options? Which of the above seems most likely to you, and why?