I totally understand you.
I actually feel a little jealous when people's DHs or other relatives actually have a diagnosis.
My DH and in laws just don't have the self awareness to realise they're socially/emotionally/communicatively atypical.
It's just hard as when you're surrounded by very odd (unintentionally rude) social practices you end up feeling like the 'odd' one for doing social niceties.
I know I'm undiagnosed ADHD. It fits to a tee. And possibly some traits of ASD that are very different to "male" ASD traits (I am generalising here but not meaning to offend) but I wouldn't have enough traits to impair my life and don't believe it would meet threshold for any diagnosis. But on the other hand, I wonder if some of these traits are now learnt behaviour from being surrounded by DH and his family...
My DH and his mother will just walk in each others houses and even right past each other. For example, if my DH agreed to cut down a tree a few days prior, he'd just let himself in his mum's house, she could be standing at the kitchen worktop and he'd literally just walk past her with all his equipment, he might even barge past her gently if she was in his way. No hello, no acknowledgement, just a bang of the back door and an off he goes to work. She might then go outside a bit later and say "he's working hard" third person as first person is too intimate, whilst wringing her hands and hopping from foot to foot.
I may come along "Hiya! You ok ?" And may get a snort and half laugh then talked over "my tree" (points to tree)
I go away feeling baffled. But to them it's completely normal and I'm the odd one.