When did you realise you were straight?

I am not joking. I am legitimately asking. I just saw a video from Shanespeare about hetero-pessimism and towards the end she half jokingly asks this question. But I legitimately looked back on my life and asked myself "oh yeah that's true when did I realise I was straight?" Wby?

Btw, for me, it was because I had a crush on this character called adrien from a mobile game called choices from their virtual "book" called blood bound ⁄(⁄ ⁄·⁄ω⁄·⁄ ⁄)⁄