If you make sure the baby knows you're playing when you do it (make sure it's an act of love not violence O.o), it won't traumatize them. I mean my dad did it to me all the time, and I'm perfectly fi... well. XD
I don't think it goes strictly by gender; it seems to have more to do with who is best suited for the job. I've read here and there that the Tsahik is usually (but not always) a woman, and the Olo'eyktan is usually (but not always) a man; rather, the positions are occupied by whoever has the strongest connection to Eywa (Tsahik) or by the senior hunter with the greatest leadership ability (Olo'eyktan). We know that many Na'vi women are hunters, and some must be fine leaders. Likewise, there must be some very wise men amongst the shamans' ranks.
I'm not sure there even was a heredity principle. If not, the practice would be similar to that of the Roman "adoptive emperors" of the Antonine era (late 90's-mid-100's CE). The reigning emperor would choose his successor based on ability, then adopt him into the family for purposes of inheriting the office. I'm thinking the 'legitimate heir' concept isn't really a feature of Na'vi culture. If Sully's hoisting his kid overhead a la Pride Rock, it's only because he's heard of the Lion King...and Neytiri hasn't, which is why she's freaking: "What are you *doing*?", indeed! <g>
(Ahh, ask Marius a silly question...get a lesson in cultural anthropology. Sorry...!) <ducks, looking sheepish>
Poor baby.Jake just had to traumatize him.But I bet the baby(And Neytiri) will REALLY be traumatized when they either a)watch the Dark Knight(Specificaly every single scene with Heath Ledger as the Joker) or b)When jake tells the "were do babies come from" story.XD