I’ve never heard of that, personally (and I’m ace-aro, in case you mean for me specifically, not super sure where that actually fits). For me I’m pretty sure it’s because I’m 2 standard deviations below average height for adult women, and furniture isn’t actually made for kids’ proportions, unless it’s for toddler-size kids. My feet don’t touch the ground in 90% of chairs, which puts uncomfortable pressure on the back of my legs, so I have a strong aversion to sitting normally. My short cousins are all the same way.

I thought this was just the “nerd who spends all day at a computer coupled with a strong nonchalance toward proper etiquette” (possibly neurospicy) stereotype. I could be equally mistaken tho.