Expert: Susan M. Heim - 5/27/2009

Question
My grandmother was an identical twin. My mother has a twin brother. My husbands mother is an identical. My nephew has twin girls. My sons wife is pregant, what are their chances of having twins. I also have a daughter, what would her chances of having twins be?

Answer
Wow, you do have a lot of twins in your family! Experts say that identical twins are just a fluke. An egg just happens to split in two. However, with fraternal twins, there may be some inheritance involved. The women in a particular family might be more likely to ovulate more than one egg per cycle, which could be an inherited trait. So, therefore, your son's wife probably doesn't have a greater chance of having twins unless there are fraternal twins on HER side of the family. Your daughter might have a higher chance since her great-grandmother had fraternal twins. So, having twins is a complicated combination of inheritance and just plain luck! It's very hard to predict when they will show up.

Warm wishes,
Susan Heim
www.twinstalk.com