Nature, not Nurture

(Illustration from TS2)

I've been a "morning person" since the Eighties and have long believed that that characteristic was instilled by having to be out the door on weekdays by 6:30 a.m. Having been retired for over ten years has not broken me of the early-rising habit, which raises the possibility of a genetic explanation: [bold added]

new research suggests DNA inherited from our extinct Neanderthal cousins ups the chance we’re early risers.

Our circadian rhythms—the biological clocks inside our cells that time when we sleep and wake—are linked to countless genes. Now researchers say they have found that bits of genetic code passed down to some of us from Neanderthals relate to our sleeping habits in the present day. The study was published Thursday in the journal Genome Biology and Evolution.

“We’ve found many Neanderthal variants that consistently associate with a propensity for being a morning person,” said Tony Capra, an evolutionary geneticist at the University of California, San Francisco and co-author of the new work. “Their effects are in the context of hundreds of other genes, but it is suggestive there is something meaningful about this.”

Being a carrier of Neanderthal genes explains a lot of things to partners (incuding mine) of early risers.