Kane Watch: May? Partly?

In his Thursday column, Eugene Kane discusses how parents may sometimes be blind to their children's bad sides in the context of Michael Ray Green, who killed Jimmy John's driver Joseph Munz, and the two suspects in the murder of Betty Jones and her two sons.

Regarding the latter, Kane says...

Suspects are in custody for the murders; it's a safe bet the parents of these
young black suspects - one just a boy at 15 - can't recognize their children
either. And yes, that may be partly their fault.

The boy is fifteen. FIFTEEN! I could understand how someone who may be in their mid-twenties, long seperated from the daily influence of their parents, may not be able to attribute too much blame to their parents, but the kid is FIFTEEN!

May and partly have no place in that sentence.