Conclusion: The twinbirth ratios of Qingdao ascends from 1987 to 2002. The difference in distribution and the seasonal variation are notable.
结论：青岛地区1987~2002年双生子出生比呈现上升趋势，有明显季节和地区分布差异。
2
Even more bizarre, a woman conceived from a split embryo could give birth to her own twin.
更奇怪的是，一个从分裂胚胎中受孕的妇女可以生下自己的双胞胎。
3
But twin studies took a surprising twist in the 1980s, with the arrival of studies into identical twins who had been separated at birth and reunited as adults.