The very best identity/Social Security numbers to steal are those belonging to those under the age of 18. ID and numbers can be safely used for a decade or more with complete safety.
Today, all newborns are issued Social Security numbers. Even before the huge Equifax breach, every year some 18-year-olds and older individuals discover their identity had been stolen and used for many, many years. They normally only discover this theft when they go to apply for a student or car loan.
Since children have no need for credit checks, all parents should freeze their children’s credit with all three agencies. Then they will have the peace of mind, knowing there will be no horrific surprises, years from now, when their children will need a clean credit history.
I think everyone with children should consider this.