I'm going to defend N52 New Gods for a bit:

Darkseid and Highfather being siblings doesn't actually sound that bad, because if Izaya is Orion's uncle, then it would make a lot more sense for Orion to be ignorant of his true parentage for a while, because then Izaya would look somewhat like him and any question could just be met by "eh you took after your mom". Otherwise, it would make Orion look quite dumb.

Also, I think the point of black-haired soviet-ish Izaya is that this is NOT the space hippie Izaya we know, but the badass warrior who lost those he loved because of Darkseid and kicked a lot of ass, until he realized the emptyness of it all and changed. Seeing Izaya BEFORE his character development is actually interesting and I wish it was explored more.

The New Gods live outside our universe and don't quite play by our rules of space and time, so different versions of the characters appearing at different points in time is business as usual.