Heidi Klum -- Good Genes or Good Docs?

Heidi Klum's look is always runway ready!

Here’s a 25-year-old version of the Victoria's Secret Angel at a party in New York City back in 1998 (left) and 18 years later ... the angelic "America's Got Talent" host – who celebrated her 43rd birthday this week – at an awards show last month (right).

“Auf Wiedersehen.”

The question is ...