So I am extremely sorry about any false rumors I have been helping to spread around the internet. I know that the Nino post is one of the most-viewed posts on my blog, so I can only hope that everyone who was misinformed will click back here and read this correction.
To set all your minds at ease, I will assure you that when I write anecdotes or facts about our five boys, I generally know or have a memory of obtaining such information from a first-hand source like an interview or a show where the information comes from either the members themselves or other celebrities who know them. In this case, I remembered reading a magazine translation where Arashi reminisced on what their first days as a Johnny's Jr were like and that's where I got the tidbit about Nino feeling uncomfortable about being poor. But because of my sloppiness (of course), I now cannot find this translation again. Which really teaches me a lesson. So I have resolved to be more principled about internet misinformation, especially in the English J-pop fandom where first hand sources are not always readily available.
So if there is a fact or something that you read in this blog and are curious or dubious about, please feel free to leave a comment (you can comment anonymously even if you don't have a blogger account so anyone can comment!) to ask me about it and I will gladly provide whatever sources I used to get at that fact. And if I can't come up with a first-hand source, I will remove the offending fact and post a correction. Fair enough?
Now onto the details about Nino's family background... (honestly, I don't even care that much for probing into his family background, but I feel like I owe it to you all to do my research extra-properly since I misled you all before).
Right now, I'll just say that Nino doesn't talk about this matter very much, and to be honest, it's really none of our business. From my googling/LJing/Tumblring of the English-speaking fandom, I've determined so far that neither Nino nor anyone who knows him has ever stated that his parents are divorced or that he is estranged from his father or that he grew up poor. All I know about his family for sure is the following:
He has an older sister and lived with his mother growing up (this is stated/implied in many of Arashi's shows, interviews, radio talks etc. so I won't bother posting a source since it's accepted). Whether his father lived with them is not stated.
In this magazine translation by Huxley, Nino (who was then still a Jr.) says that when his family gathers around, he's the only male around. I guess that implies that his father is not present at such gatherings, which suggests some estrangement of his father from the rest of the family. But still, estrangement does not equal divorce.
In this other magazine translation also by Huxley, Aiba (who was then still a Jr. also) actually says that he has visited Nino's house and met Nino's father. Aiba was surprised at how young Ninomiya Sr. was. So this kind of contradicts what Nino says himself in the first source, since Nino is obviously not the only male in his family! But then, who knows the full details of Nino's family life? There could obviously be many possible situations that accommodate both Nino and Aiba's accounts.
Thanks to bouncer78 for pointing out that in Ep. 31 of Mago Mago Arashi (aired 2005.11.26), around the 8:25 mark, Nino talks about how he used to poor and would eat scented/flavored tissue papers as food. The exact phrase he used was "昔, 本当にお金なくてね." My Japanese is not great, so correct me if I'm wrong, but I think that this could be taken many different ways. He uses "mukashi," which just means "in the past," so we can't really conclude that he was talking about his childhood when he made this statement about being poor. Also, as bouncer78 also pointed out, this was in a pretty informal environment, so Nino could totally just have been trolling everyone, too.
Thanks also to Jana Lott for telling us about the 2004.07.10 episode of Ai no Apron (愛のエプロン), on which Nino talked about his family. I haven't actually watched it because I couldn't find it, but I just thought I would list this as a source for anyone who is interested. Jana also provided this link to a tumblr post in which some fans talk about Nino's family based on the speculations from some Japanese forums (they link to those Japanese forum posts, too). Not a first-hand source, but it might be of some interest to some.
ETA: @lysanderpuck from Twitter has kindly provided this informal fan discussion concerning Nino's relationship with his father. No first-hand sources, but an interesting read if you're THAT obsessed with this topic.