My daughter has a neighbor with 3 children. There is a set of 4 year old twins and a 3 year old. All 3 were conceived through in vitro. The weirdest aspect of it is that the 3 year old is a triplet of the twins. Her embryo wasn't implanted with theirs. Now their dilemma is that they have a few more frozen embryos and don't know what to do with them.
And that is the other reason I vehemently oppose in vitro. To me it's no different than abortion. In fact, in some ways it's worse. My blood ran cold when a friend of mine, who has had 2 babies by in vitro, told me she'd rather destroy (i.e. kill) their left-over embryos (i.e. unwanted babies) than to give them to someone else to raise.