I have an identical twin brother! They were both born from the same pregnancy. Do you have any twins in your family? 
My two little sisters were twins. How do twins develope?
Well there are two types. The first are identical, where they develop from the same zygote. Fraternal twins develop from two separate eggs! What type are your sisters?
Fraternal. We thought they were gonna be identical.
Interesting! They were both fertilized by a different sperm cell in this case. Do you know much about human biology? 
Not much really. Is there anything more you could me about it?
Of course! Sometimes there are non-related people who look very similar. These people are referred to as doppelgangers. Do you have a doppelganger?