I don't know where to put this thread but I hope this would fit in here.

My youngest brother has mild autism. He can talk, eat, act, think, and do like a normal person does. But his mental ability is very late. I mean he will be 21 this coming November but his character is more of a teenager of 14 and 15. My dad told me that he started talking when he was 2 years old while me and my brother who came after me talked when we were at the age of 1 year old.

My parents are just as normal as everyone else. But what might be the reason why my mother conceived a not-so-normal child? She didn't drink alcohol or smoke, so as my father. We are 3 brothers (no sisters, my mom is the only girl in the family) and both me and my brother next to me is normal in mental ability. But as I have said already, our youngest brother has a delayed mental development. What could be the causes?

I have no idea, have you done any research?

I had my research but I want more opinions and thoughts about this. It is still unclear to me how a very normal parent would have a child that is not so normal. Honestly, even though I have a brother like that, I don't want to raise a child like him. I have seen the difficulties of raising him. And also I don't like the teases that my brother is receiving from our neighbors and from his playmates. I can't do nothing to help him so if possible I would not like to have a child like him.

Thanks for the interest in my inquiry though.

Good to learn something new each day, if able. Have you been tested yourself, do you know if it is hereditary?