Awful casting, Hollywood.
The young age of everyone involved, including accomplished scientific and family man Reed Richards, and the black Human Torch, noticeable because his sister is as blond and white as they can get, are just two huge elephants in that room that will resonate on anyone that notice it, and the movie will have to overcome.
I mean sheesh dude, you can just say the kid is adopted. It's not that hard at all.
I am not saying it is hard, I am saying they have to make it work.
If they decide that he/she is adopted or they are half brothers, it is something the script should address at some point. To change something like the race of half a couple brothers and act like the backstory or the dynamic of their relationship would not be affected at all would break the suspension of disbelief for some people. At that point, they should just go with them being totally unrelated, but that is also a pickle because they share the same last name. And it does seems unnecessarily contrived that, in a team of 4 people that are mostly unrelated (so there is no restrictions for making some, or all of them Asian, Latino, black or even Eskimo, if they want), they decided to change one of the two people that are written to be blood related. As people has said here, if they casted Jordan as Reed Richards, there would be a lot less detractors.
The same happens with the age issue. They need to try, really hard, to make me believe 26 years old Teller is a super scientist, physicist, astronaut and family man. The same way they tried (and failed) to convince me Jessica Alba was a lead scientist/astronaut in the previous one, and Denise Richards was a world renowned nuclear physicist in James Bond. Even when considering one can be a super model and a scientist at the same time, there is the fact they would be too young to be accomplished in all those fields. If they tried with a more traditional casting (like calling an actor that actually looks like a smart in his mid 30s), they wouldn't have to try so hard not to sell me the characters.
At this point, we don't know. As far as we can tell they are all perfect for their parts and give award winner performances, but if the movie doesn't address these issues about the characters and their relationships, I still don't think its going to work.