Okay, so I was trying to determine the biological basis for my earlier remembrances and did a little research. Without getting into XOs and XXYs too much (this is complicated stuff), random notes on self-impregnation:

Parthenogenesis; non-sexual reproduction i.e. development of the ovum into an individual without fertilization by a spermatozoon. Common in the insect and fish world plus a few other higher animals, but usually considered not possible among humans. Although eggs develop by themselves fairly often, they do not develope very far. However, several studies in the 19th century discovered pregnant women who carried to term who had some sort of vaginal blockage and could not have been (as far as they knew at the time) inseminated by men. Also, in 1955, Lancet reported a "virgin birth" where researchers could not rule out parthenogenesis.

In parthenogenic offspring, the female's 23 chromosomes double to make up for the missing male chromosomes. So parthenogenic offspring are a clone of the mother.

(Parthenogenisis among some frog species' was the basis of the dinosaurs' reproduction in Jurassic Park, except that the movie also combined it up with another phenomena, namely spontaneous sex change, which can happen among some species as well.)

Hermaphroditism; a sex anomaly in which gonads for both sexes are present; the external genitalia show traits of both sexes and chromosomes show male female mosaicism (xx/xy). Hermaphrodites can impregnante themselves (even without resorting to physical measures.

Quote, "In a study in the Netherlands in 1990 called Combined Hermaphroditism and Auto-fertilization in a Domestic Rabbit. In this study a true hermaphrodite rabbit served several females and sired more than 250 young of both sexes. In the next breeding season, the rabbit which was housed in isolation, became pregnant and delivered seven healthy young of both sexes. It was kept in isolation and when autopsied was again pregnant and demonstrated two functional ovaries and two infertile testes. A chromosome preparation revealed a diploid number of autosomes and two sex chromosomes of uncertain configuration.

A study was carried out on a human hermaphrodite at the Department of Obstetrics and Gynaecology, Chicago, Lying-in Hospital, Illinois. The objective of this research was to determine the conceptional events resulting in a 46xx, 46xy true hermaphrodite and to report the first pregnancy in a 46xx, 46xy true hermaphrodite with an ovotestis.

The design of this study involved chromosome studies performed on patient's lymphocytes and fibroblasts, red cell antigens, human leucocytes antigens and the presence of y- chromosome deoxyribonucleic acid were analyzed. Findings were compared with parental and sibling blood group data.

The result of these studies demonstrated that our patient is a chimera; an organism in which there are at-least two kinds of tissue differing in their genetic constitution, thus with dual maternal and paternal contributions. In addition, despite the presence of an ovotestis, she conceived and delivered a child."

Chimera - A chimera is an animal compirsed of cell lines from a variety of sources. They can be found by fusing two or more early embryos or by adding extra cells. Reproducable in labs on mice. At least one such human subject is a alive and has been the subject of many scientific studies. His skin is male XY, but his blood is female YY. This particular subject has a face which has one appearance on one side, and a significantly different appearance on the other, but it otherwise is a perfectly normal appearing boy. It is not 100% how he came into being. The possibility exists that he had a female fraternal twin in the womb which died, and some of that twin's genetic material passed into his body. OR -- they merged in the womb. Another theory is that his mother parthogenically reproduced, then part of the egg was fertilizied by the father before the embryo died.

Finally, many children are born without being 100% of one sex or the other and are also not true xx/xy hermaphrodites -- sometimes with drastic appearance anomolies, but often very minor ones that may go unnoticed. In the case of children who are of fuzzier distinction, a sex is generally chosen and the child raised that way. Sometimes operations are performed to "correct" physical anomalies, but actual chromosonal makeup is rarely checked, and the determination is made by appearance alone. An XY child can appear totally female, or vice versa, but XY females cannot generally conceive normally.

So -- if Mary were a true hermaphrodite or a chimera (or even just a bit mixedup), the process of parthenogensis could have created a male child and not just a clone. As I said, pretty rare.

To a believer, the upshot of all this can mean that Jesus' birth was a divine miracle, yet of natural origin. To a skeptic, this can mean that God wasn't required, necessarily.