People who work with Loki have strongly gotten the message that they are older, and sons of Loki's mother Laufey from before she took up with Loki's father Farbauti. So they'd be half-brothers. But that's people's intuition.
I had the IMPRESSION they were older, too. I just don't know why, so I can't put that down as fact so I just drew it.
I'm going off of tons of my own research from multiple sources. Unfortunately, I can't say that I have any backing other than tons of books, time, and research. I'm going into mythology as my field of studdy, but that's a few years from now.
I have some help, but it's mostly me on the ohdeargods team. If you could tell me where you got this information, it would be very helpful! I love getting my hands on new material!
I know a lot of Loki's people. (I'm a Hel's man myself.) One of the greatest was Fuensanta Plaza, who was an amazing mystic dedicated to Loki and Sigyn. (The Heathen author Galina Krasskova is her daughter.) I had the privilege of being friends with Fuensanta for several years before she died (and it was indeed a privilege). She would go into trance and speak to spirits, and as Loki was her main deity, she wanted to know every single one of his relatives. It was she who first brought up those two, and she said that she'd spoken to Laufey and got this information. Later, others also came up with it separately. But it is god-connection, not written sources. And it seems that your pieces, which I've enjoyed seeing go by, are all primary source material. Which is fine, but I don't want to pretend I'm talking about anything documentable.
I love stuff like this, and you're so lucky! I'm extremely jealous.
I would love to have other sources, but I'm a silly girl in Canada who just happens to love mythology to the point of obsession. I want to go into the mythology field, and go places and find things... But for the moment, I can't. All I have is a mountain of books and a heart full of ambition.
If you read the other comment on this page, evidently they are, in fact, older. I've never seen that before, though. I've never seen anything on them in the Eddas or in the research material I have on hand.