I'd be surprised if either of the Sureshs had powers, mostly because I assume Papa Suresh would have started off by testing himself and his kids if they had the requisite genetic marker.
As for Ando, I actually think it's better for the storyline if he DOESNT have any powers. It makes the sweet friendship/protective thing he has with Hiro even sweeter, and it makes his willingness to go into such dangerous/potentially deadly situations even more noble, since he knows he doesn't have any "specialness."
his dead sister did...
You mean Mohinder's dead sister? I'm still not sure what I think about that...Papa Suresh was talking about it at some point, and he seemed to hint that her "genetic mutation" was cancer or some similar disease that killed her, which is why he now searches for the positive manifestations of that kind of mutation. Then again, they were keeping it deliberately mysterious, so maybe she DID have a power. If she did, I think that would bolster my conclusion though, because Papa Suresh would definitely have tested Mohinder for the genetic marker and would have definitely told him if he had it. And even if Papa Suresh hadn't done it, Mohinder himself would probably have gotten curious by this point and checked himself out.
In another, somewhat unrelated note, I'm wondering about all the people who might have died without ever triggering their powers...like, for example, Claire seemed to develop her power pretty early on in life, but we know that people like Nathan and Peter didn't trigger theirs until much later, so theoretically they could have died young and never figured out what they were capable of.