Personal observation. Since the topic is deeply important to the mental health and happiness of a large fraction of the entire human population but sounds slightly silly, I would not particularly expect any significant experiments to have been done by academic science. Surveys of percentage actually practicing polyamory, yes, attempts to directly determine a wish / tendency / suitability in a general population, no.
This is falsifiable if Carl or Jonah want to check cynicism, though I wouldn't be too surprised (the Kinsey Institute exists).
.. I would also expect this to be a low-research area, but not due to sounding silly, but rather due to high-noise datasets. People lie about their sexual desires a lot. This particular desire is even more likely to be denied or concealed from researchers than most, so I would expect most people setting out to look into this to get to the "Design data-collection protocol" stage, acquire a monumental headache, and then go research which kind of diet is easiest to stick with instead.
This is a thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. The previous "stupid" questions thread went to over 800 comments in two and a half weeks, so I think it's time for a new one.