Halsey -- Good Genes or Good Docs?!

"Thinkin' you could live without" Halsey's fire looks over the years is just straight up wrong!

Here is a 21-year-old version of the blue-haired hottie at SXSW in Austin, Texas (left). This was the year she dropped her debut studio album, "Badlands" and it was all good from there!

And, nearly a decade later, the uber-talented musician -- who turns 30 years old today -- recently took her rockin' crimson vibes to the 2024 MTV Video Music Awards and had the world seeing red with her stunning looks.

We know she'll be ringin' in her dirty 30 ... but the question here is: