James W H
Ann Hum Biol. 1980 May-Jun;7(3):273-6. doi: 10.1080/03014468000004321.
There is evidence, both direct and indirect, that there is a continuum in sex ratis across the various sorts of twin zygote. The evidence for low sex ratios is strong in respect of the rarer sorts of twins (monoamniotic and conjoined), but the contrast between dichorionic monozygotic and monochorionic monozygotic pairs is suggestive too.
有直接和间接证据表明，在各类双胞胎合子中，性别比例存在一个连续统。在较罕见的双胞胎类型（单羊膜囊和联体双胞胎）中，低性别比例的证据很充分，但双绒毛膜单卵双胞胎和单绒毛膜单卵双胞胎之间的差异也具有启发性。
