My boyfriend's dad freaked out when he met me

After 6 months of dating my (29) boyfriend(30), he took me to meet his dad and I remember very well his face when he saw me, he was scared thinking his son might be committing a crime or something. He literally pulled my boyfriend aside and just said "wait a bit, I have to tell him something important", he thought I was underage or just turned 18 and was extremely worried, after we cleared it up he asked me my routine to look young.

And now that I think about it, when I met my boyfriend he also asked me my age several times because he didn't believe me, makeup helps, but people still believe I'm a teenager trying to pass as an adult.

ETA: Thank you all for sharing your stories, I'm having a blast reading this thread!