Check out EOB 2013 edition 1A.36 and 1A37. There is a discussion on this very similar scenario.
I'll closely type the section.
Minor children attribution not disregarded. Although a husband and wife might not be attributed each other's ownership interests in the respective businesses, if the have minor children (under 21), other attribution rules may result in a controlled group relationship. Under the stated facts of the example, Husband and Wife are not attributed each other's ownership interests in their respective businesses. Normally then, Husband's wholly-owned corporation would not be part of a controlled group with Wife's wholly-owned corporation, because the companies have no common owners. But suppose they have a minor child. The minor child is attributed the stock in each company. This creates a controlled group relationship because the minor child, as the common owner by attribution, owns 100% of each company.
Comment: controversy on this issue. .......At a Q&A session with the IRS at the 2012ASPPA annual conference, IRS representatives indicated that, until there is a statutory change made by Congress, the IRS would follow the literal wording of the statute.