I have two teenagers. My daughter is 15 and is typically developing other than the fact she has mild ADHD. However she met all of her milestones on time.
My son is 13 and has mild autism and severe ADHD, and because of that he has special needs.
I will just say it's quite an experience being in both worlds. With my daughter I celebrated her progress and milestones such as when she started walking, speaking, going to school, and graduating elementary school. She is now in high school and is now interested in boys. She has her friends, and in a few years she will learn to drive and go to college. She wants to eventually settle down and have a family of her own. I told her to not rush into it and to do some traveling before hand.
However, it's a different and far more challenging ballgame with raising my son. As soon as he was diagnosed with autism due to his lack of speech, lack of interest in social interaction and extreme tantrums he immediately went to have ABA therapy since he was 3. He has never been able to make friends and even though he is verbal you can't have a typical conversation with him.
My daughter was potty trained completely by 4. She wasn't ready before that but my son was 6 when he was potty trained. Fortunately he got there and we needed extra help from therapists with training him.
My daughter has some ADHD and has an IEP because of it. However she just finished grade 9 as expected. My son can't go to a public school and has never been in any grade. He has always been in a school for kids with special needs. But the important thing is that he has been able to learn and one day he will be able to work. He has had to have intensive therapy through out his life.
However there is one thing that is for certain. All kids are meant to evolve and leave the nest (however some move back home due to finances or unfortunate circumstances on their part). Typical kids go to school, graduate high school, go to college, find a job and a place of their own and create their own lives.
Some kids with special needs may end up following that route as well. However, the majority don't like my son most likely won't. He won't drive or go to college. However he will be moving into a group home and find employment through agencies that help find work for people with disabilities. So yes, they do evolve but in a different way. At the end of the day the result is the same anyway.
In another post in the future I will write about kids with disabilities reaching adulthood.