Why does Thanos love his adopted daughter more than his biological daughter?

Thanos doesn’t have any biological children, only adopted.

Corvus Glaive

He was an alien from a planet, modified and enhanced to speak. He was trained to be proficient in his glaive.

The only way for him to die is for his glaive to be destroyed, or to kill him with it — like Vision did.

Cull Obsidian

He was the brother of Corvus Glaive, enhanced to be a better weapon. He was enhanced to the point of being the strongest in Thanos’ empire.

Ebony Maw

He was yet another alien who was enhanced to be the smartest of Thanos’ empire, while also having telekinesis. He is also the leader of the Black Order and Thanos’ second favorite child.

Gamora

Gamora was picked out by Thanos to become a warrior for him. She was trained to become the replacement for Thanos one day, surpassing her sisters, Nebula and Proxima Midnight.

Nebula

She was picked from her conquered planet by Proxima Midnight to be a better companion to Gamora. She is also Thanos’ least favorite child.

Proxima Midnight

She is the sister of Ebony Maw and is the final alien experimented upon, and was enhanced to become proficient with her spear. She is also the wife of Corvus Glaive.