^ This
When I was 18 and out for lunch with my mother and grandmother, my mother was asked if I needed a kids menu (11 and under). This memory has been ingrained in me to the point of bitterness whenever my age is assumed. When I was in my 20's I was constantly beaned as a teenager. Even now I'm still only getting 20 to maybe 25 if I'm already visibly offended by "you're too young for [x]" which is ablest in itself.

My best friend took her cousin to her high school opening, they have around a 10 year age gap. While the cousin was checking the place out, my friend was asked what grade she is. "Oh, I graduated college some years ago, also I'm married."

When style is involved it blurs even farther. I have a colorful, cutesy-esque style; even my adults with older children look fairly young.