据报道,南京铁路分局某建筑队一名工人的3个孩子全都是精神发育迟缓、智力低下者:19岁的大女儿和15岁的二女儿均不会收拾房间、不识字、不懂得用钱买东西、怕羞避人、语言能力低下、动作迟钝、表情呆滞,连一位数加减法也不会算;一个10岁的儿子智力更差,更衣洗澡不能自理,思维简单、动作笨拙。这是为什么呢? It is reported that all three of the workers in a construction team at the Nanjing Railway Branch are mentally slow and mentally retarded: the 19-year-old eldest daughter and the second daughter of 15 years old will not clean up the room, illiterate and do not know how to spend money Buying things, being afraid of shyness, poor verbal ability, sluggish behavior, sluggish expressions, and even one-digit additions and subtractions do not count; a 10-year-old son is less intelligent and can not take care of himself in changing clothes and takes a simple thought. Why is this?