When your entire family is a music, art, book, computer, or history nut and owns more books than a library.
When you are planning your honeymoon and opt for a historical site instead of the beach.
(Or when your family throws you a history themed shower - and one of your former history teachers is there)
When you stay up late sitting on pins and needles just to see if DH actually fixed the laptop that broke 2 years ago.
When you get a kick out of spreadsheets or get a high off creating really complicated ones.
When you actually get cravings to play your favorite instrument.
When you are so type A that you come up with 10 songs rather than the original 3 that were requested by your music group...
When talking about having kids, you choose names from Star Wars books or from Beatles songs and imagine that your kids will be just as nerdy as you.