...would be identical if the two twins were impregnated at around the same time? Similar to twins being impregnated and born minutes later after each other?
2006-08-25 04:19:29 · 10 answers · asked by Source 4 in Science & Mathematics ➔ Other - Science
No. The time of impregnation is completely irrelevant. It doesn't matter if conception happens 5 seconds or 5 years later.
(Incidentally, I don't think anyone understood your question correctly ... it took me a careful reading to see that you are asking specifically about the *time* of conception.)
I think you are confusing the moment of conception and the moment of birth. I.e. from your last sentence, you seem to believe that the closer in time twins are "impregnated" [conceived] and born determines their chances of being identical twins. That's not how it works.
Identical twins are indeed *born* a few minutes apart, but they are not *conceived* minutes, or even seconds, apart ... they are *conceived* at the EXACT SAME INSTANT .. because it is the EXACT SAME EVENT (the moment of fertilization). In other words fertilization of the egg cell by a sperm cell happens once, and then the fertilized embryo (zygote) splits into two, producing two identical embryos. Nine months later, the two are born a few minutes apart only because there's no room for both to emerge at the same time.
Fraternal twins can be conceived at the same instant, or a few seconds or minutes or even hours apart. But fraternal twins are no more genetically identical than any two normal siblings. (Which is why fraternal twins can be different genders.) That's because fraternal twins are simply when two random sperm cells happen to fertilize two egg cells, resulting in a double-pregnancy (two normal non-identical siblings who happen to share the same pregnancy).
It is *theoretically* possible that two fraternal twins could be genetically identical. For this to happen, an identical sperm cell would have to fertilize an identical ovum. (If this happened at the same instant that would be pure coincidence ... it would most likely happen a few minutes, or even hours, apart.) But the odds of two identical sperm fertilizing two identical eggs are so infinitessimally tiny, it is barely worth mentioning. I.e. a couple would have to have a few *billion* pregnancies for this to occur once.
The same would hold for two normal siblings born in two different pregnancies. Incredibly slim chance of two brothers by different pregnancies being genetically identical.
And the same would hold for two children of two twin couples as you describe ... where the two fathers are genetically identical; and the two mothers are genetically identical. From a purely genetic point of view, this is no different than the same couple having two babies in two different pregnancies, or the same couple having a pair of fraternal twins (two non-identical babies in the same pregnancy).
Hope that helps. (Ask for more details if you have questions.)
2006-08-25 07:58:34 · answer #1 · answered by secretsauce 7 · 1⤊ 0⤋
This can be a very interesitng question! I do not think they are going to be same in the experience that they will look precisely alike, given that there are mutations of the twins' (the moms and dads) DNA in the first position (even though very mild). Nurture also plays a gigantic section in the differing apparences of the youngsters. As far as the DNA being exactly the same being the definition of an equal twin and how that is created, i have never located expertise about that. I did to find two sites that were necessary in trying to get an answer for this question, although. I will be watching extra into this as good. Just desired to state that consistent with the third website online I've listed beneath, Chang and Eng did not marry twins as Kak (just a few above) stated.
2016-08-09 12:33:36 · answer #2 · answered by capoccia 4 · 0⤊ 0⤋
They would not be identical. Assuming that the mothers and fathers are identical twins, the cousins would have a genetic relatedness of 50%, just like siblings. They might be slightly less similar than a pair of siblings because the hormonal regimes in the uteri of the two mothers may be more different than in two pregnancies of the same mother. Suppose one of the two mothers was smoking or taking medication, for example.
I can't imagine how the time of conception could matter. Maybe if there was extreme difference - if one of the two mothers got pregnant at the age of 40 or something.
2006-08-25 04:38:38 · answer #3 · answered by helene_thygesen 4 · 0⤊ 0⤋
Identical twins (also called "monozygotic twins") are the product of a single conception event - that is, one sperm meets one egg and forms a single zygote. The zygote then divides into two (genetically identical) cells, as per usual - however, at the two-cell stage it becomes separated. Until the 16-cell stage, these cells are all completely identical - that is, each one is fully capable of developing on its own into a fetus.
This is different from fraternal twins, which are the result of more than one sperm meeting more than one egg. That is, there are two separate conception events, and thus two genetically distinct zygotes/individuals.
In the scenario you describe, the odds of genetically identical individuals emerging are astronomically small. It would require identical sperm from each male twin meeting identical eggs from each female twin - theoretically possible, since both contain the same DNA, but since eggs and sperm are formed by randomly picking half of the DNA from the parent, the odds are very small. We can work it out as, at MOST, 1 in 70,368,744,177,664.
2006-09-01 10:59:24 · answer #4 · answered by astazangasta 5 · 0⤊ 0⤋
it somewhat is an extremely interesitng question! i've got not got self belief they are going to be comparable interior the experience that they are going to look precisely alike, using fact there are mutations of the twins' (the dad and mom) DNA interior the 1st place (in spite of the shown fact that very fair). Nurture additionally performs a huge section interior the differing apparences of the youngsters. as a techniques using fact the DNA being precisely the comparable being the definition of an comparable twin and how it somewhat is created, i've got no longer stumbled on suggestion approximately that. I did discover 2 websites that have been useful in attempting to get an answer for this question, nevertheless. i would be finding further into this to boot. basically wanted to state that for the period of accordance to the 0.33 internet site i've got listed under, Chang and Eng did no longer marry twins as Kak (some above) reported.
2016-09-29 23:36:37 · answer #5 · answered by ? 4 · 0⤊ 0⤋
the kids wont be identical cuz theyre not from the same egg or sperm. in twins, the dna in the sex cell are probably differnet because of meiosis.
2006-08-25 04:22:57 · answer #6 · answered by cookie 2 · 1⤊ 0⤋
No, twins tend to skip a generation
2006-09-01 10:38:02 · answer #7 · answered by TheDude 3 · 0⤊ 0⤋
twins run in families so yeah it ups the odds of having twins
2006-08-25 06:28:15 · answer #8 · answered by shiara_blade 6 · 0⤊ 0⤋
well, even though the children are cousins, they are also genetically brother and sister since each of their parents has the exact same set of genes
2006-09-01 11:29:49 · answer #9 · answered by ~*Prodigious*~ 3 · 0⤊ 0⤋
Possible. But not certain
2006-08-25 04:23:08 · answer #10 · answered by Dr M 5 · 0⤊ 0⤋