Where (in-game or otherwise) does it say that Hakon and Gormlaith are blood siblings? I myself have seen no evidence of this and want to know if it is true and what source it's from. Anyone who can help, I will be deeply grateful.
In one line of dialogue Gormlaith calls Hakon her brother, whether that is literal or figurative is not known.
It's completely unknown whether they are related in that way or not. Gormlaith does refer to Hakon as "brother", but she could have meant that as shield-brother or blood-brother, there is no solid evidence, I'm afraid.
Makes sense to take that little bit out until someone finds actual canon confirmation, no?
Yes, it does.
And I think it would be a good idea to point that out int he Trivia section. As in, write that it's unknown whether Gormlaith is Hakon's actual brother or not.
Sometimes people in groups call each other brother and sister Ex. Dark brotherhood, companions
That's not what we're questioning here. Please read more carefully next time.
I'll update it, (aka moving the reference to Hakon being her brother to the trivia section with a note that it is not known if they are truly related by blood or not.