Various groups at https://a.gup.pe/

https://www.tylervigen.com/spurious-correlations

https://www.tylervigen.com/spurious-correlations

50% genetics and 50% the twin’s respective environment. These twin studies often look at twins separated and raised in different households.

Twin studies show thats its about 50% each.

Buying there is worse for devs as this is credit card fraud to buy keys and the devs will have to do chargebacks. Devs prefer piracy over key resellers.