You might be right. I am not a native EN speaker, so that might play a role too.

My wife has severe ADHD. All our kids too (diagnosed and medicated). One of them is AuDHD, with a “harder” autism gradient (?) compared to me… She does have severe social interaction problems.

For me it’s been strange - I have CPTSD, growing up autistic in a household that would “pray the gay away”… not easy. I moved out as soon as I could. But I’ve lived all my life by heavily masking. I learned how to behave from TV shows and observing others. Social interactions have always been a “show” for me. Only after I got diagnosed it started to make sense…

Ok, it’s a developmental disability, but it’s also on a large spectrum. I only got diagnosed in my 40s. I lived my life as “the weird one”, but even after I got diagnosed, I still don’t consider myself “disabled”…

Just acknowledge it, without being weird about it. It’s not a disability. I joke about my ASD, and make fun of my ADHD wife (and the other way around).

Ask if they need anything, and don’t be high context, be direct. I don’t know your brother’s situation, but I personally struggle reading between the lines. I take things literally.