▁that ▁there ▁is ▁no ▁possibility ▁of ▁any ▁classific atory ▁c ous ins ▁sharing ▁the ▁same ▁mother . ▁Because ▁mat ernal ▁identity ▁is ▁never ▁in ▁question , ▁they ▁would ▁be ▁automatically ▁class ified ▁as ▁sib lings . ▁Only ▁mistaken ▁pat ern ity ▁leads ▁to ▁such ▁errors . ▁ ▁This ▁possibility ▁is ▁much ▁less ▁likely ▁for ▁cross - c ous ins , ▁because ▁in ▁the ▁absence ▁of ▁full - s ib ling ▁inc est , ▁it ▁is ▁unlikely ▁that ▁cross - c ous ins ▁can ▁share ▁a ▁father ▁by ▁over t ▁or ▁cover t ▁sexual ▁relationships . ▁It ▁would ▁only ▁be ▁possible ▁if ▁a ▁subject ' s ▁mother ▁had ▁a ▁brother ▁whose ▁wife ▁was ▁im pre gn ated ▁by ▁the ▁subject ' s ▁father , ▁thereby ▁allowing ▁apparent ▁cross - c ous ins ▁to ▁be ▁cover t ▁half - s ib lings , ▁sharing ▁the ▁same ▁father . ▁ ▁Middle ▁Eastern ▁parallel ▁cousin ▁marriage ▁And rey ▁Kor ot ay ev ▁claimed ▁that ▁Islam ization ▁was ▁a ▁strong ▁and ▁significant ▁predict or ▁of ▁parallel ▁cousin ▁( father ' s ▁brother ' s ▁daughter ▁- ▁FB D ) ▁marriage . ▁He ▁has ▁shown ▁that ▁while ▁there ▁is ▁a ▁clear ▁functional ▁connection ▁between ▁Islam ▁and ▁FB D ▁marriage , ▁the ▁pres cription ▁to ▁marry ▁a ▁FB D ▁does ▁not ▁appear ▁to ▁be ▁sufficient ▁to ▁persu ade ▁people ▁to ▁marry ▁thus , ▁even ▁if ▁the ▁marriage ▁brings ▁with ▁it ▁economic ▁advantages . ▁According ▁to ▁Kor ot ay ev , ▁a ▁system atic ▁accept ance ▁of ▁parallel ▁cousin ▁marriage ▁took