Poppy I was single when my AC came to live with me and we also lived in a 'stepford' type community. I felt like the mum in the song 'Harper Valley PTA'! I subsequently discovered the apparently perfect families with dads in prison, alcoholism, domestic violence, granny actually doing most of the caring rather than parents etc.
I'd totally agree with others that this is not an adoption issue but a single parent family issue. I'm now in a relationship but don't live together with my partner full time. Whilst there's a view that 2 parents are better than 1 I'd also say that the fact me and my AC have a lot of time together on our own is a huge bonus. She gets lots of my attention, which she needs, and we have a closeness that I think we'd lose if there was anyone else living with us full time. Adopted children in particular need a lot of one to one to give them reassurance.
As it happens I grew up in a single parent family too, just my mum and 4 other siblings. I'm really grateful that as there was no dad around I got enough one to one time with my mum even though there were 5 of us. We called her our MAD which is a mum and dad rolled into one!
As for books I would recommend 'Who's in a family?' by Robert Skutch, it discussed all sorts of families including single, same sex, and animals. We also have 'Do I have a daddy?' by Jean Warren Lindsay but I didn't like that as much.
As for normal families my AD has a half brother she sees regularly, 3 half siblings we've never met and are never likely to, and 2 older step-siblings who she has never lived with but adores. 3 out of the 4 of my siblings are step-parents too. We don't have a family tree we have a family orchard that spreads far and wide!