Hello..... Your 12 year old son is a male and in the middle of puberty so YES - he will as a male be turned on by visual stimulation, even at this young age - it just comes with the territory of having testosterone in his body.

And - IMO - I would say that your son is upset about you showing skin not because he is attracted to you, but rather he is upset to how his friends may see you - since you are not their mother..... and YES young boys even at the young tender age of twelve do indeed talk about females and how hot they are (mothers included).

LoVe,
Rhapsody - (mother of 2 boys - 22 & 17)