Recently, a question was asked about the possibility of the words knee and generation being cognates. Unfortunately, that question is rather unclear, so I'm asking this as a separate post.
The words in question are commonly derived from the PIE words *ǵónu 'knee' and *ǵenh₁- 'to give birth, to beget', respectively. The obvious similarity between these two reconstructed forms would be easy to dismiss as a chance resemblance, especially given the lack of an obvious semantic connection. However, it reminded me of a curious parallel in Basque: belaun 'knee' and belaunaldi 'generation' (with -aldi meaning 'period').
It seems someone else has also noticed this interesting parallel (though their other blog posts look a bit dubious at first glance): https://oldeuropeanculture.blogspot.com/2015/11/from-knee-to-knee.html They also point out Finnish sukupolvi 'generation' from suku 'kin' + polvi 'knee'.
So there seems to be a connection between the concepts 'knee' and 'generation' in at least three unrelated language families. Has this been treated before in the scientific literature? Is there an obvious connection that I'm just missing (maybe via joint/changing directions/changing generations)? Is it based on a specific concept common to the prehistoric cultures of Europe that's since been forgotten? Or is the parallel formation based on calquing?