> In that case your chance of having an opposite gender twin should be about half a percent.
Only if you assume half of all twins are opposite sex, which is wrong; that may be correct for fraternal twins (though since environment at conception seems to affect sex, maybe not), but it certainly isn't for identical twins which are always the same sex (by sex chromosomes, at least.)
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[ 4.3 ms ] story [ 11.8 ms ] threadOnly if you assume half of all twins are opposite sex, which is wrong; that may be correct for fraternal twins (though since environment at conception seems to affect sex, maybe not), but it certainly isn't for identical twins which are always the same sex (by sex chromosomes, at least.)