lightbrite,
If they tell you that when they grow up they want to do a non-frum job?
What’s a non-frum job?
Or if your boy says that he wants to do a girl job (dunno what but there must be something)?
Or if your daughter wants to do a boy job (like be a rabbi)?
Do you say that you cannot do that because you are frum or it goes against Torah?
I would strongly recommend against saying that, because a young child doesn’t yet fully understand the concept of “against Torah”, or even most of the concepts the Torah is addressing. S/He can, however, feel rejected and hurt. I think it’s better to try and connect with the child’s feelings underpinning the statement, and then to gently redirect if needed.
To take another example, it’s very normal for a toddler to say something like, “when I grow up, I’m going to marry mommy!” Would a sharp, unintelligible (to him) response be appropriate, making him feel like his desire for connection with his mother is a bad thing, and she hates him? Or would a hug be best, followed with something like, “G-d willing, you will grow up to be an erliche young man, and Hashem will help you marry and have a family of your own, and your mommy will always be your mommy, and she loves you so much and will always love you.”