Well, I imagine you won't believe me, but I will tell you nonetheless my memory.
I must have been 8 or so, I was alone at home watching the telly and my favourite speakerin appears on the screen to announce the afternoon TV programs. I get an instant huge erection (the first in absolute that I remember) and, without knowing what I am doing and why, come closer to the TV set and put my dick where she has her mouth... (maybe also risking an electric shock).
I grew up in a very catholic family and for sure did not know anything at that time about sex and oral sex in particular. It must definitely have to do with genetics...

Best regards,

Lino