Was Thanos Born Purple?

Thanos was one of the last sons of A'Lars, progenitor of the second colony of Eternals on Titan, and Sui-San, the last survivor of the original settlement of Eternals in this moon. He was born with purple, hide-like skin and a massive body due to his Deviant Syndrome.

Why was Thanos born purple?

But to get back to our question, 'Why is Thanos purple? ', it is because of a genetic disorder that afflicted him since the time of his birth, that bore the Deviant strain in his otherwise Eternal body.

How did Thanos get purple skin?

Though Thanos was born to two Eternals (A'lars and Sui-San), his body carries the Deviant gene. That's why he has mottled purple skin and a disfigured chin whereas the rest of his family could more or less pass for human.