This is an amusing bug. I gave my son a new pair of clothes and instead of wearing them all he's in now is underwear.

this also happened to me XD but with mu daughter i gave lucia the green girls dress cuz i thought it would be cute ...poof shes in her green underwear lol they i tried to give the same dress to ger sister ren and its just fine XD weird isnt it

P.S she looks dirty in her underwear she needs a bath

Though I think it is a bit more normal to have a son doing it rather than a daughter.

If you give them more clothes they'll put them on, that's what I did.

if you give them clothes of the same color they are wearing
it seems the clothes go invisible
easy fix just give them a different color