There's a very obvious spot to "poll" the PC for this, at the birthday party right after the Overseer give you your Pip boy. Amata asks you if you know what she got you for your birthday, and one of the questions is A Date with Christine Kendall/Freddie Gomez... or I guess, technically, /two/ of the questions are those, but one is filtered out by your gender. So all you have to do is take out the other possible responses and the filter, so that the player has two choices - the date with the boy or the date with the girl. If the PC is male and chooses the male name or female and chooses the female name, you activate a GayPC flag on the character, and then do whatever you're going to do with that information. I thought about adding it to my modding, but honestly I didn't see much point. The character doesn't really demonstrate a sexuality anyway, nor is sexuality really prevalant in any quest chain or storyline. We're just not that high up Maslow's pyramid with all the water still mucked up, y'know? ;)