Semi-Identical Twins Are Double Delight for Geneticists
An Australian brother and sister born in 2014 share the same DNA on their maternal side but just some of their father’s — the result of two sperm cells fertilizing one egg — according to a report yesterday in The New England Journal of Medicine. The sesquizygotic siblings are just the second-known case of semi-identical twins, and the first to be discovered in utero.
Is there a health risk? Their “extraordinarily rare” genetics make the twins susceptible to an uncommon form of cancer, but doctors will be keeping a close eye on the pair.