I don't know anything about adoption but wanted to add my (maybe helpful) experience as the parent of a child with autism and someone who knows lots of parents of children with autism.
All the things kristinam said apply to either my child and family or families and children I know!! They are all bio children from loving nurturing backgrounds, no drink or drugs involved in pregnancy, children very much loved and wanted.
These children explode into their families like IEDs! The impact can be devastating. Nearly every parent I know is on antidepressants. People's marriages do implode. Some people I know can never eat out with their children and only go to 'safe' places where everyone understands.
I personally worry a lot about the impact on his NT sibling of his brothers SN! I get dismissed by all and sundry (he is fine, he is lovely, why do you want to label him). Even when they do agree there is an issue, you can't get support because as a family we are not 'deprived' enough! And ds1 isn't 'bad' enough (NB this means distuptive! He is pulling out his own eyelashes, but this is not a 'visible' sign of distress)
Other people will say to you ALL the time, my child does that too! Either competitively or dismissively!
I think the point I am trying to make us that while its incredibly hards and I usually feel like I am failing, you survive because you have to and because your child depends on you. And all the mothers I know with SN children had NO idea it was coming, it just exploded their lives.
Our children are a huge joy too, I love my son dearly, but I would not have chosen this life. Now that I have it I just gave to do my best in it! I have no choice.
One of the things that people say about parents of sen kids is that special children are sent to special parents! Which IMO is patronising bollocks!
I did see somewhere, sen parents become special because we have to and I actually quite like that. I have certainly discovered depths of patience and perservearance I never knew I had.
I suppose what I am trying to say, at 3am, as I can't sleep while worrying about ds1, is these problems are really real and really hard, they dominate everything about family life, every aspect if it, the impact on siblings is profound. I spend all my time feeling like I am failing as a mother! So really, really think about the impact on you, your family, your child! Because SN of any kind, from any reason are incredibly hard and when they are 'hidden' its really fucking hard because no one makes any allowances at all!!
I hope you don't mind me crashing your adoption thread, specially as I have absolutely no experience of adoption at all, KristinaM's posts just really spoke to me and I wanted to highlight the pact that issues with a child can have on your life!