As always you need to consider a probabilistic model that describes how the school distributes children among classes. Possibilities:
- The school takes care that all classes have the same number of foreign nationals.
- The school even tries to make certain that each nationality is represented roughly the same in every class.
- The school doesn't consider nationality at all and just distributes randomly or based on other criteria.
All of these are reasonable. Given strategy 2 the answer to your question is no. When they use strategy 3, the expectation will be close to 3, but a bit smaller. That is because your son takes up a "slot", and you have one less chance for a random Italian.
When the school uses strategy 1 the expectation also goes up; how much depends on the number of foreign nationals per class.
Without knowing your school there is no way to answer this more perfectly. If you have just one class per year and the admission criteria are as described the answer would be the same as for 3 above.
Calculating for 3 in detail:
$$E(X) = 1 + E(B(29, 2/30)) = 1 + 1.9333 = 2.9333.$$
X is the number of Italian children in the class. The 1 comes from the known child, the 29 are the rest of the class and 2/30 is the probability for an unknown kid being Italian given what the school says. B is the binomial distribution.
Note that starting with $E(X|X\geq1)$ does not give the proper answer, as knowing that a specific child is Italian violates the exchangeability assumed by the binomial distribution. Compare this with the boy or girl paradox, where it makes a difference whether you know that one child is a girl vs. knowing that the older child is a girl.