If you read the article closely, I think you'll find that the baby will still basically have only 2 genetic parents. I think that mitochondrial DNA is outside the nucleus of the egg, and doesn't combine with the rest of the DNA when the egg and sperm unite. The mitochondrial DNA of the donor egg would indeed be passed on to the child. But the child's genes would actually come from the the sperm, and from only one egg, which would actually supply the genetic material. Mitochondrial DNA is a form of non-recombinant DNA.