[Chickensoup]

I think that the twins are not optimal specimens of humans.

Baby girl and blood clot and lost arm then had ovaries removed because they were sub optimal.

Have no idea of cognitive ability.

[Tax-chick]

some of both embryos’ cells contained two X chromosomes, while other cells contained an X and a Y chromosome.

This is very unusual, and it would likely have a negative impact on reproductive organs. The blood clot might have just come up.

[ApplegateRanch]

Look up ‘freemartin’. Somewhat common in cattle; now, it seems to also (very rarely) occur in humans, too.