The team found that people with four or more siblings (either younger or older) were twice as likely to hae deeloped certain types of brain and nerous-system tumours than those with no siblings.

• 这个小组发现有四到五个同胞的人（不论年幼或年长）患脑及神经系统肿瘤的机会比没有同胞的人高约两倍。