3 ms·

I think with genetic sequencing we’re way past this belief.

• edgyquant 4y ago
  We are not. There are some suggestions that they might be biological but it is not a settled matter at all.
  • dahinds 4y ago
    It is absolutely settled. The genetic basis of chronotype has been extensively studied in fruit flys and mice, and parallel effects in the same genes have been found in humans.