Personally, I would treat it the same as any choice that gives you pause. When I've seen players taking different sex or gender characters, it's mostly because they want to safely explore that identity, so I would assume that's the case here. I haven't personally encountered behaviour that I or my group found disconcerting from that, but maybe we've been lucky. On the other hand, if a player wants to be kender, that worries me because they typically either want to be disruptive (and my group doesn't welcome PVP action) or they want to try playing it positively - which can be fine, if they really know what they're doing, but can go poorly.

In those cases I would try to engage with them before committing to characters and try to gently talk about their motivations. Try to figure out what appeals to them about this character and how that might work.

Also, if you have a problem with players acting fetishistically, it might be worth sitting down with your players and creating some sort of safe word for "this is making me uncomfortable". We have that, it doesn't get used much, but it is very handy.