Question about retcons made to Colossus

I guess the title is a bit misleading, but what retcons were possibly made to Colossus’ backgrounds or relatives?
The first issues he appeared in didn’t seem to mention or indicating to him having a brother until when they went to save Jane & co. Same could be said to his sister being a mutant. Would these be considered as such retcons in order to make him more ‘interesting’ or such?

Not too sure about when his sister became recognized as a mutant. I remember he had a brother who lived in an alternate dimension, too. (Lol, John Byrne!!!) This brother was introduced in the '90s, so I guess that counts as a retcon of sorts. And I think the most recent Colossus miniseries established that he’s a direct descendant of Grigori Rasputin.

I think having an insane brother who lived in an alternate dimension and being descended from Rasputin is even sillier than being a gay member of the Russian mob, but that’s just me.

His return from the grave was a big one. It was handled very well though.

Granted I don’t think he’s had any major retcons, writers just added things to the character over time.

Ah I see, thanks for the info though, it was confusing me when I read about his origins and about his siblings later on.