Are they interested in coding? Do they have independent learning material on computing?
So were I and my girlfriend. So did we. We are now senior product developers (and team leaders) in highly rated companies.
Do they have irregular sleeping patterns?
Both my daughter and I are diagnosed as being nocturnal. We are forced to function in a world of diurnal people. Of course we have irregular sleeping patterns.
As a kid, I did a lot of camping with the only technology brought along being flashlights and walkie-talkie 2-way radios. We minimized using the flashlights and radios. We even put out our fire at sunset. Did not "reset" me in to being diurnal. Actually made me more nocturnal. We've taken our daughter camping many times, following the same "rules". Like me, our daughter didn't become diurnal. Even a week in a medically supervised sleep lab didn't change either of us. And we know many others who are also nocturnal and we have plenty of face-to-face social contact with them.
Do they get an income from their online activities, do you know why and how?
Both my girlfriend and I did. Again, we turned to be productive good citizens.
Have they become more socially isolated?
Social isolation is not limited to nerds. The fact that nerds are more likely to be socially isolated is far more a problem with how our society treats technically competent people. Things like this list of "signs of potential cyber criminality" just re-enforce the problem.
Are they resistant when asked what they do online?
Both my girlfriend and I were. Normal for kids, especially teenagers. Our daughter was/is less so - but she knows (some of) what we did online at her age.
If either my girlfriend or I had turned criminal, why would it not have been cyber crime? As a kid, I had a friend who was a very good magician. She could have turned out to be a very good pick-pocket thief. Instead, she's a pediatrician who's very good at distracting her patients from pain.
Criminal specialization is no different normal work specialization. Also, there are far more non-nerd criminals than nerdy ones.