On Mon, Apr 02, 2007 at 12:57:12PM -0700, Judy Ryder wrote: > > well, one can imagine a pair of siblings (incl. fraternal twins) who > > happened to share exactly 50% of their dna. and if they were franternal > > twins, they'd also share prenatal environment. but you'd have to do a > > pretty serious amount of looking to see exactly what % of their genomes > > were shared, and of course *which* genes would matter, too... > > > How about if the egg splits and is fertilized by two different sperm? > Half-identical?
i've never heard of an unfertilized egg splitting. that said, you'd probably end up with more than 50% shared dna in that case, averaging 75% (since the sperm are unliikely, althuogh it's possible, to come from different people). but this is a bit blue-sky, since an unfertilized egg splitting would be very peculiar. --vicka
