Help?

So I've come to think about what my parents told me when I found out I'm seeing a guy who is six years older than me (he's 24, i'm 18):

"What does a 24 year old grown man see on an 18 year old high schooler?"

Take note that I feel insulted with this question. I know we are in different stages of life but I am more myself when I'm around older and grown people.