A person is related to any other person if the person bears a relationship to such other person specified in section
267
(b) or
707
(b)(1), or such person and such other person are engaged in trades or businesses under common control (within the meaning of subsections (a) and (b) of section
52). For purposes of the preceding sentence, in applying section
267
(b) or
707
(b)(1), “10 percent” shall be substituted for “50 percent”.