Requirements for twins???

Oddly, I've actually also seen it when twins are adopted from the same SWI to different parents, at different times. Seemingly, they are abandoned at different times and different places, possibly because the b-parents do not think that twins are desirable for adoption. There was a child in our daughter's SWI who was adopted a month earlier. they look very similar, but this child's papers say that she is 3 weeks older than our daughter. I still follow their blog, and still think they are very similar in look and stature. If they are sisters, they are not identical. But I've seen at least 3 sets that are identical, and adopted separately but from the same SWI. In all the cases, the parents of one was browsing the internet and looking at the older SWI pictures, and found a child that struck them as the same as their own child, but had a different Chinese name. There might not be a significant number, but I do wonder how many actual twins identical or fraternal are separated at birth or by the SWI.