Ooh, good topic! I've realised I was so freakin judgy when I was younger and a long way off having kids. One friend had her first baby at... Hmmm... 20, I think? Which really did not seem like reproducing age back then!!

I heard she slept with her boy in her bed. Little judgy in my head said "uh oh, better get him in his own room or he'll never get out of her bed!" Now at 15 months Miss A is still in a cot next to my bed and nine nights out of ten winds up in my bed.
I thought at a certain age you just did controlled crying. No questions asked. A kid's gotta learn to sleep right?
I thought it was normal that at a certain age babies start having 'toddler milk'. Whether you're breastfeeding or not, at some point they'll need toddler milk.
Along the same lines, I never thought I would breastfeed for so long. I knew I would breastfeed, but I didn't know about natural, self-weaning. I think I kind assumed it would end quite early.

I'm certain there are more. Like I said, I was judgy, and it's amazing how a bit of research and a child of my own has changed me! Thankfully I never said any of these judgements aloud, I was still supportive