Yes, he looks like he could be 19, but that's the thing with a lot of guys- they look younger than their age. Models like Marcel Castenmiller, Mark Cox, Johannes Niermann and Ryan Koning all look younger than their age. I was surprised to learn that they are all in their mid-twenties. Since I posted my original comment, I went back and took another look at some of Nessman and Coupe's pictures, especially any personal photos where there's little to no make-up or styling involved. And I will say, they do look younger to me now. But that does not change the fact that Nessman is an old soul- he's extremely mature for his age, not to say that he can't be 19/20 but it does still cast some doubt in my mind.
Recently FmenTV did a little promo feature on Benoni Loos and they had his birth year listed as 1984; NYmagazine has him listed as being born in 1987. Here's another: Jonatan Frenk is listed as being born in 1993/1992 in his thread, but in his mtccasting video he says he's 22. So... EDIT: I also found two different years of birth listed for Nessman as well.