Bill Nye -- Good Genes Or Good Docs?!

It's Bill Nye's 67th birthday and his looks over the years will have you questioning the relativity of gravity!

Here is a 50-year-old version of 'The Science Guy' looking spiffy and ready to experiment at The Planetary Society's Gala in Arcadia, California back in 2005 (left). This was more than a decade after he began sharing his quirky and educational personality on his hit show "Bill Nye The Science Guy."

And, 17 years later the TV personality recently fancied up at an environmental media event in Los Angeles (right). He may have ditched the lab coat, but he'll forever rock his signature bow tie look.

'Bill, Bill, Bill!'

The question is ...