这是一篇短文，讲到有些人天生有“共感(synesthesia)”，
例如听觉并味觉（听到声音的时候，觉得声音有味道）、不同字母有不同的颜色。
目前科学家初步认为这是基因的关系。
"Currently, synesthesia is not completely understood, but it is believed to
be in our genes. Scientists find that the white matter of synesthetes is
organized differently from that of people without synesthesia. This may
account for the differences in perception. Nontheless, some scientists think
all people _____________ with synesthesia only to lose it later on in their
lives."
(A)were born (B)may be born
(C)may have been born (D)may not have been born
空格处答案是C。请问为什么？A、B、C有什么不同？谢谢！