Bar Mitzva for Gentiles

After much time wasted in the comments section, back to some meaningful bloging.

Rav Shlomo Fisher, Shlit"a brings up an interesting question. Does a gentile have a concept of a bar-mitzva? In other words, at what age is a gentile obligated in the 7 Noahide laws?

Rav Fisher quotes the chatam sofer (Y"D 317) who writes that every gentile is obligated in the Noahide laws from the age at which they reach intellectual maturity. Based on the Chattam Sofer, both the Ohr Sameach and Rav Yitzchak Elchana Spektor write that a Jewish child who has reached intellectual maturity but is not yet bar-mitzva, is obligated in the 7 Noachide laws. While it is true that the child is excluded from any punishment for the 7 laws, he is nonetheless obligated in keeping them.

Rav Fisher brings another proof to this effect from a Gemara in Ketuvot (11a). The gemara says that a minor who is going through a conversion process is brought to the mikvah based on the da'at of the beit din and when he grows up and becomes bar-mitzva, he can protest his conversion if he wishes. The question arises as to age what point can he possibly protest. Before his bar-mitzva, the protest is meaningless and after, it is too late. The tosefot Rid explains that the point at which he can protest is between the age at which he reached intellectual maturity and his bar-mitzva.