I know this is normal for three-year-olds, but I have trouble not reacting negatively to it. I don't want to encourage this behavior, so I try to ignore it. But the more I ignore it, the more involved he becomes with it. My older son also engaged in this type of play, but not to this extent. Should I be worried or should I let it go?
At age three, your son is still forming his own identity and may play with many kinds of toys. Just as your older son did, your three-year-old may in time move to playing with stereotypical "boy" games and toys. Make sure that your son has access to clothes and toys that are traditionally worn and used by boys.
You can also find dress-up clothes for male-stereotyped jobs. React positively when your son plays with these things and encourage him to play with his older brother and other boys in your neighborhood.