This seems to be affected by dress or appearance. When I'm dressed casually, I seem younger. a round baby-ish face doesn't help either. When I m dressed professionally, I appear older. Figures.
Clean shaven...remove 2-5 years.
With a beard or other form of facial hair...add 1-2 years.
Standing next to a (truthfully older) sibling...add 3-5 years.
Playing hide and go seek with my little cousins...remove 10-15 years (it's a sight to see).
My 12 year old ISTJ daughter recently told me, "Mom, you're not like other moms. I asked her what she meant and she replied, "Firstly, you don't look your age. You look 35 and don't act old." Coming from an ISTJ I knew that was a sincere compliment.