Paternity test identical twins

Tsu

This was a topic of conversation in my biology study group a gazillion years ago. Even after all these years, I never got an 'official' answer to this question! Also, in the ovulation of two eggs -- does this happen simultaneously or can several hours (or days!) pass between the release of each egg?

LURCH

That's actually a pretty fascinating field of research. The advantage of the last male has alot to do with the shape of the human penis (a fact only recently discovered, I believe). But the amount of advantage is as much a matter of psychology as physiology. It has long been known that these two factors are perhaps more closely related in the reproductive system than anywhere else. If, for example, a husband believes that his wife may be cheating on him, the composition of his ejaculation can actually be changed by that idea. He will still produce sperm of the usual type we all know and love, the type designed to empregnate (call it "reproductive sperm"). But he will also produce "spermicidal sperm", which act to prevent empregnation by another male. These spermicidal sperm come in two basic kinds; an active and a passive kind.

Passive spermicidal spermatizoa swim a certain distance and then stop, looping their flagela into a form resembling a fishing hook. Millions of these become entangled by each other's tails, forming a berrier. The active veriant swim about bumping into others. If the other sperm they bump into does not match the chemical signature of the husband, they attack and kill it chemically, then continue on searching for more. These are the wto types I know of, there may be more.

It's real warfare in there!

Aiza

Standard paternity testing examines 16 DNA markers which is enough to make them over 99.99% accurate. In the case of the State of Missouri and Holly Marie Adams vs. Raymon and Richard Miller, the paternity test showed that the two brothers both had a 99.999% probability of being the father. There is currently no commercially available test that can determine which of the twin brothers passed his DNA to the child even though there are ways in which the genomes of identical twins differ.

Borek

Yes. Few weeks ago such a case hit news in Poland. It was seventh case known to science. Sorry, I have link in Polish only (but Google translates page reasonably well).

http://wiadomosci.gazeta.pl/Wiadomos...odmy_taki.html

If not for Aiza necropost I would never find post from 2004.

Phrak

I don't know what all the fuss is about. In most cases, the father is the one who doesn't give birth. He's the one who's not screaming "I'm going to kill you for this."

DanP

Do you have research papers pointing to this specific type of sperm competition in humans ? Including for the claim that expression of certain genes governing type of sperms is regulated by a nebulous stress response to "my wife is cheating on me" ?

It makes no sense to have this type of sperm competition selectively triggered on and off in humans.

Humans are half way between tournament species and pair bonding ones, females are not strictly monogamous, and more importantly, nor are men, so the mechanism to evolve (should it exist) would be most likely not triggered by a stress response, but active all the time.

DanP

This cracks me up. Listen to that, in most cases the father doesn't give birth

sovereignty

Remember people, that twining is hereditary in females. If the mother is a twin she has a higher chance of having twins herself. Also older mothers have a higher chance (and IVF and other treatments increase the chance). Male twins have even odds as singletons (A person that is not a twin or other multiple birth) males of having twins.

And this is just for non identical twins.

"Some twins -- fraternal or dizygotic twins only -- are the result of hyperovulation, a female tendency to release multiple eggs during ovulation. If two -- or three or more -- eggs are fertilized and implant, the result is twins or multiples. Hyperovulation can be a genetic tendency, so if a mother has the gene for it, her daughter might also. In that sense, it can be said that twins run in the family, but on the mother's side only. Fathers don't ovulate, so they don't impact twinning in this scenario. "

from http://multiples.about.com/b/2009/07...hereditary.htm

Kinase

I'm an identical twin, theres two other sets of identical twins in my family, and a couple fraternal sets. Consequently people always ask me stuff like this and I never no the answer... and am mistaken for my brother a lot.

DaveC426913

Twice this thread was necroposted. The first time was seven years.