My ten pence worth, I was 40 before I even considered having kids but then met the woman of my dreams and love paved the way forward. She had 2 boys, 8 and 10 (both with mental health issues) but I took them on as my own (the power of love) as their father was long gone and still to this day doesn't keep in touch. Within 2 years my partner became pregnant and we had a wee boy. He is 19 now and we all get along fine, he was home educated by my wife as she's an ex teacher and has strong views about the education system, especially how messed up it is in Scotland where we now live. Three years ago her eldest son who was in his late 20's had a daughter and due to his ongoing issues was unable to care for her, so we took her on from birth full time as legal guardians/foster parents.
I have to say having a 3 year old girl buzzing around the house in my 60's is certainly not what I was expecting to do after our youngest grew up, but it is THE BEST thing in the world and we wouldn't have it any other way. To paraphrase Billy Connolly, "we're here to look after the place and care for the children, I mean what else is life for?" I couldn't agree more!