My preferance is sister, mainly due to the fact that since I do not have a sister its harder for my brain to think too much about the whole thing. like I enjoy incest in games, forbidden fruit tastes best, but like Irl I want nothing to do with the idea. However if my mind can avoid making me...
Pregnancy is usually a turn off for me, but every now and again it winds up being some focus. However if in a story a character would be pregnant from me(mc) then its not necessarily a huge turn off.
Usually faceless protags or protags that I usually don't see the face can appeal more, however realistically so long as the face isnt either off-putting or a super big focus of a game I really find myself not caring the most.
Mine was a duo, I really found myself liking both raven and starfire in the original run of the teen titans cartoon, and to this day both of them are semi-consistent focuses of mine
If I am being honest I can't remember when I started gaming, some of the first games I can actively recall are diablo 2 and fate. But if I am being honest playing games has been a constant part of my life, my dad and brothers all played games and I just kinda started before forming real memories