2006-12-30 12:35:40 · 19 answers · asked by Barbara H 1 in Pregnancy & Parenting ➔ Pregnancy
Identical twins means that they were once the same zygote and then split during embryo division.
Since a zygote is composed of an egg and 1 sperm (either X for a girl or Y for a boy), then the resulting twins would have to be of the same sex.
Fraternal twins allow the possibility of a boy and a girl. That results from having two separate, fertilized embryos.
2006-12-30 12:41:36 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Identical twins must be the same sex- two boys or two girls.
However- have you ever seen fraternal twins that look a -lot- alike? This can happen if the egg splits and then is fertilized by two different sperm- which means that both twins get identical DNA from the mother. This is most likely why Mary Kate and Ashley Olsen look so much alike even though they are fraternal, or non-identical twins. This could happen with a boy and girl set of fraternal twins as well. This type of twins is called "polar" twins.
There's also a very rare occurrence that can cause identical twins of two different sexes- if you're interested, see this page and Turner syndrome: http://encarta.msn.com/encnet/features/columns/?article=twinsmorethan
2006-12-30 13:01:33 · answer #2 · answered by Muir 2 · 0⤊ 0⤋
Maternial twins come from the same egg which produces identical twins which one sperm (which determine the sex) fertlizes the egg and then the egg splits into two. So yes the are the same sex. If the aren't the same sex then the a fraternal twins.
2006-12-30 12:46:50 · answer #3 · answered by Stina 1 · 0⤊ 0⤋
Identical twins are IDENTICAL (that means the same). Fraternal twins can be a boy and a girl.
2006-12-30 12:38:47 · answer #4 · answered by Kirsten K 2 · 0⤊ 0⤋
Identical twins HAVE to be of the same sex or they're not identical. (In case you didn't know, boys have a penis and girls have a vagina)
2006-12-30 18:16:56 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Identical twins are only the same sex. boy and girl twins are fraternal.
2006-12-30 12:37:54 · answer #6 · answered by missjewl 3 · 2⤊ 0⤋
Identical twins are of the same sex Paternal twins can be a boy and a girl
2006-12-30 12:39:06 · answer #7 · answered by what gives 4 · 0⤊ 3⤋
You can't have identical twins of different sexes. Identical twins have matching DNA and that is impossible if you are of different sexes.
2006-12-30 15:50:09 · answer #8 · answered by sweetin30349 2 · 0⤊ 0⤋
Identical twins are formed from one egg that split. They will either be two boy/girls.
2006-12-30 12:38:43 · answer #9 · answered by lifeisbeautiful 3 · 0⤊ 0⤋
identical have to be the same sex
2006-12-30 12:45:51 · answer #10 · answered by Anonymous · 0⤊ 0⤋