XY gives usual male.
XX gives usual female.
X gives Turner’s (syndrome).
XXY gives Klinefelter’s (syndrome).
XYY gives “XYY male”.
(syndrome) is in brackets, as apparently not every individual with the genotype will go on to manifest the syndrome.
The latter three genetic variations will not necessarily cause miscarriage, nor, at least for XXY, sterility. XXY seems to be a functional variant, and given the rates, there may be well be a couple of individuals with that genotype on the SDMB.
Frogstein and AKAmame:
It is important to note that fertilization of one egg by two sperm would not just cause trisomy of the sex chromosomes (Kleinfelter’s, “supermale”, et al.), but would cause Triploidy, having three copies of every chromosome. This is possible, but does not bode well for the fetus:
Yes twins do often display this symmetry (about 25% IIRC). Trouble is it’s caused by environmental factors, not genetics and can’t be used to determine paternity and won’t have any effect on the baby.
wevets, you are correct about the triploidy. On re-reading frogstein’s post, I discovered that I had mentally removed the ‘one egg, two sperm’ bit, and just processed the ‘one X two Y bit’ and replied accordingly. An interesting example of selective reading, but embarassing to have made the error nonetheless.
I suspect I also owe a mental apology to frogstein for my comment of