ɐkˈoːɹdɪŋ tə sˈuːpɚmˌæn ænd dˈɑːktɚ lˈaɪt, ðɪ ˈɛkstɹə kɹˈoʊməsˌoʊm pəzˈɛst baɪ mˈɛmbɚz ʌvðə zˈɛnoʊbɹˌuːd ɪz ðə sˈoːɹs ʌv ðɛɹ sˈuːpɚhjˌuːmən ɐbˈɪləɾiz.
According to Superman and Doctor Light, the extra chromosome possessed by members of the Xenobrood is the source of their superhuman abilities.