Forum Friday: Are Twins Hereditary?
Friday July 10, 2009
A guest writes: "Is giving birth to twins hereditary ? Or does it just increase your chances? My partner is a twin (not identical). My mother is a twin (identical). Also on fathers side my Great Grandmother gave birth to twins. (identical) I was just wondering as no one else in the family has giving birth to twins except for a cousin of my fathers. Is it a myth?"
Ahhh, the great "twin gene" question. Do you have to have a family history to have twins? Is twinning hereditary?
The answer is ... sometimes. Some twins -- fraternal or dizygotic twins only -- are the result of hyperovulation, a female tendency to release multiple eggs during ovulation. If two -- or three or more -- eggs are fertilized and implant, the result is twins or multiples. Hyperovulation can be a genetic tendency, so if a mother has the gene for it, her daughter might also. In that sense, it can be said that twins run in the family, but on the mother's side only. Fathers don't ovulate, so they don't impact twinning in this scenario.
Not all dizygotic twins are due to family history. Other factors besides genetics can cause hyperovulation, such as fertility treatments, birth control pills, breastfeeding, advanced maternal age, and even dairy products.
A genetic impact on monozygotic (identical) twinning has never been identified. That's not to say that clusters of identical twins don't repeat within families. However, you can't credit it to -- or blame it on -- genetics. Call it fate or coincidence, or just plain good luck.
So let's look back to the original question. Is this message forum guest likely to have twins? What do you think? Stop by the message forum and share your input.
More resources:
• The Twin Gene: Do Twins Run in Families?
• How to Have Twins
• Identical or Fraternal? Understanding Zygosity
Ahhh, the great "twin gene" question. Do you have to have a family history to have twins? Is twinning hereditary?
The answer is ... sometimes. Some twins -- fraternal or dizygotic twins only -- are the result of hyperovulation, a female tendency to release multiple eggs during ovulation. If two -- or three or more -- eggs are fertilized and implant, the result is twins or multiples. Hyperovulation can be a genetic tendency, so if a mother has the gene for it, her daughter might also. In that sense, it can be said that twins run in the family, but on the mother's side only. Fathers don't ovulate, so they don't impact twinning in this scenario.
Not all dizygotic twins are due to family history. Other factors besides genetics can cause hyperovulation, such as fertility treatments, birth control pills, breastfeeding, advanced maternal age, and even dairy products.
A genetic impact on monozygotic (identical) twinning has never been identified. That's not to say that clusters of identical twins don't repeat within families. However, you can't credit it to -- or blame it on -- genetics. Call it fate or coincidence, or just plain good luck.
So let's look back to the original question. Is this message forum guest likely to have twins? What do you think? Stop by the message forum and share your input.
More resources:
• The Twin Gene: Do Twins Run in Families?
• How to Have Twins
• Identical or Fraternal? Understanding Zygosity
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