@moonlit dream:

Ah, yes...XD But I just got really confused when I saw the Danimals commercial with Zack and Cody in it and I was like 'Did they lose one and they put a blonde wig on some guy the same height or something...?'...XD

@Wakusei Aoshi:

You, my friend, are getting down to the EXACT exacts. xD Nothing in nature is absolutely perfect.
Say you have two strawberries that came from the same "mother" strawberry. Chances are they don't look exactly the same, right? But they still have the exact same genetic code. (When strawberries reproduce, they reproduce asexually by making genetic copies of itself. Basically.)

That's the same thing with twins. (Or at least, I'm assuming...) They have the same genetic code, but they won't look entirely the same. You probably only notice differences because you're looking for them.

@Wakusei Aoshi:

dont worry i find it confusing some times too

@xNotUnderstood:

Well, my best friend's mom is like an expert on this, but when she explained it to me, I got really confused...O.o

@moonlit dream:

Yeah, but I had seen several different pictures of them to compare. The picture with Jedward, one of them looks more serious than the other and I could always pick this out...Then with Tia and Tamera, the one with the squinty eyes always seems to have squinty eyes in all the pictures I've seen her in...O.o And on the show...

Yeah, it could be their environment, but with Zack and Cody, seriously, the one with the fatter head has a fatter head, not because he could eat more but because the space between his eyes and temples are much bigger than his twin.

And, yeah, my best friend has short orange hair, which she dyed, and her sister has long blonde hair with black strips, which she also dyed. The can look different, but I'm looking at their facial features, ignoring anything they could changed...Unless they got plastic surgery...O.o

@Wakusei Aoshi:

i hope that helps.cuz i know some twins and dont worry i get em confused

@xNotUnderstood:

Hrmm...that makes sense...

I always thought Zack and Cody were fraternal twins. (I'm using their stage names because it's easier. xD;)

But you know, the twins' appearences could've been changed by the environment and such. Like, Zack could eat more than Cody or something.
And the boy on the left in the middle picture's haircut could be slightly different than his twin, making him appear to have a larger forehead. Or it could be the angle. And he could be physically doing the eyebrow-thing for the picture to make him look more serious.
And with Tia and Timara, it could be timing of when the picture was taken... Like, how they themselves position their faces may make them look different, but that's just because they won't be doing the EXACT facial expression at the EXACT same time.

(Sorry for the long explination. xD;)

As naruto uzamaki12 said, identical twins come from the same ovum/egg, so they have identical genetic material. Identical twins can ONLY be boy-boy or girl-girl, never boy-girl because the genetic code for a girl is different from a boy.
As a result, identical twins share the same traits and look the same. But that doesn't mean they're going to grow up exactly the same, because they will be effected by the environment, and end up looking different from eachother. (One could get more tan than the other by being in the sun more, one could dye his/her hair, etc...)

Fraternal twins can be boy-girl because they come from two different sperm and egg. As a result, they don't usually look the same because they get different genetic codes, but it's not uncommon if they share similar traits. I know some fraternal twins, and they look like any other brother and sister, only they have the same birthday.

Long comment. My apologies. xD;;

Identical twins:meaning that they develop from one zygote that splits and forms two embryos

fraternal Twins:because they develop from two separate eggs that are fertilized by two separate sperm

Answer your question?i know some twins