How to make twin babies
Twins and triplets are conceived in two different ways:
-when two or more eggs are released and fertilized, the result is nonidentical twins;
-when one egg is fertilized by one sperm and then divides into two separates zygotes, the result is two separate embryos. These share identical genetic structures and will therefore become identical twins.
The number of twin pregnancies has doubled compared to a generation ago. Twins now make up around two percent of all pregnancies-partly because of recent medical advances, such as in vitro fertilization and fertllity drugs ( both of which carry an increased risk of multiple pregnancy), and partly because women are having babies later in life.
Women over 35 have a greater chance of conceiving nonidentical twins because they are more likely to release more than one egg per cycle. \
Nonidentical twins also run in families. However, there are no factors that increases the risk of conceiving identical twins.