I [49F] am an aunt to an absolutely awesome kid [5M], who is my little brother [42M] and sister-in-law's [39F] son. A few weeks ago, my brother and his wife went on vacation and I got to watch my nephew for the week they were gone. My brother and his wife are both professors and are both very, very intelligent people and my nephew is no different. My nephew's days are usually highly structured and include extra time devoted to learning (mostly through working in workbooks, especially for subjects my nephew loves or that his parents don't think are taught well or enough in school, or with some nonfiction books for kids) and reading each day (amounting to about 2 hours a day).

Of course, when my nephew came to visit, I didn't plan on sticking to this kind of structure and definitely didn't plan on basically giving him homework every day. However, my nephew got really upset the first night when I said we could skip it. He also got upset the next day when I did set up his extra learning but did it at a different time than he usually does it. He also got a bit anxious when meal times weren't the same as they are when he's at home and when I suggested that we have sandwiches for dinner (because sandwiches are for lunch only, according to my nephew).

This combined with a lot of his other behaviors that I've seen before (like how he has really intense interests that he likes to talk about at length, doesn't like making eye contact except with people he's really close to, has problems playing with and making friends with other kids, etc.) lead me to believe he might be on the autism spectrum. This really wouldn't be surprising, as my brother was diagnosed with Asperger's when he was in middle school (and I wouldn't be surprised at all if the same was true of my sister-in-law) and a lot of the ways my nephew acted reminded me exactly of my brother when he was that age.

After my week watching my nephew was over, I brought all of this up to my brother and my sister-in-law and told my brother that they should take him to get a diagnosis and just talk to a psychiatrist/therapist. My brother immediately shot that down and said that there wasn't any need for that. I pressed him a little on it and his reply was a bit more snappy, but was basically the same. I let it go for the time being, but I've brought it up to him again when we were at our parents' place last weekend for our mom's birthday.

He was quite mad that I brought it up again and he told me to drop it. He said that there's nothing wrong with his son and so he's not going to treat his son like there is something wrong with him. I said that I'm not saying there's anything wrong with him either, but the fact of the matter is that seeing someone while he's still very young might be helpful so that he can fit in and make friends more easily. My brother just repeated that he's not going to treat my nephew like there's anything wrong and that was that.

I'm just worried that life is going to be harder than it has to be for my nephew because of my brother and sister-in-law's choice here. My brother was bullied a whole lot in school and had big issues making friends (he didn't have any until he met his wife when they were getting their PhDs) and I just don't want those issues to come up for my nephew and I feel like seeing someone, getting a diagnosis, and maybe talking to a therapist might be helpful for him.

Am I an asshole for bringing this up to my brother more than once? Would I be an asshole if I tried to keep bringing it up? Is this the wrong way to go about things?