Is it racist if I think positive stereotypes?

Well racist and stereotypical are two different things. Stereotyping involves generalizing a group of people, but racism specifically carries an implication that some people are superior or inferior based on their race.

The lines get blurred when you make a generalization that can be inferred to have a hierarchal point of view.

Saying black guys love rap and hip-hop or white girls love Starbucks is one thing. But it becomes an issue when you have generalizations that demean or discredit an entire race. One of the biggest examples is how for decades Blacks and Hispanics were generalized as criminals and gang members leading to racial profiling that we still see today.

As for positive stereotypes, I wouldn’t consider it inherently racist but the problem is when you say (blank) race has (X) Quality you’re implying that the other races lack (X) Quality.

Even if your intentions are in the right place, if you keep telling one son how smart he is, overtime the other children might feel inferior.

I don’t personally feel that way, but just offering a different perspective on the question.