Twin Sisters

Dizygotic twins are also more common for older mothers, with twinning rates doubling in mothers over the age of 35. With the advent of technologies and techniques to assist women in getting pregnant, the rate of fraternals has increased markedly.
Identical (monozygotic) twins
Identical or monozygotic (MZ) twins occur when a single egg is fertilized to form one zygote (hence, "monozygotic") which then divides into two separate embryos.