Can My Infertility Be Passed On to My Child?

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How likely is it that my infertility is caused by something genetic? Could I pass it on to a future child?

— Anonymous

This is a really interesting and complicated question.

One way to study this is with animal models, where researchers use mice (or other animals) to look at specific genes that are associated with infertility. These genetic links can then be explored in humans. Many individual genes have been associated with either infertility directly or with conditions (like PCOS) that are linked to lower fertility.

For the most part, the genes identified here may raise the risk of a condition, but the impacts are small. In other areas of genetics, researchers have found genes — like the BRCA gene for breast cancer — that dramatically change someone’s risk profile. The genetic mutations that relate to infertility risks are simply much less important.

A more holistic way to look at this is to ask how heritable infertility is. That is, if you knew someone’s complete genetic code, to what extent would you be able to predict infertility or low fertility? To answer this, researchers rely on twin studies. This is a common approach in genetics, effectively asking how much overlap there is in diagnosis across monozygotic (identical) twins. If something is perfectly heritable, even if the genetics are complicated, then if one twin has it, the other should. By seeing how many twin pairs share a diagnosis and how many do not, you can get a sense of how important overall genetics are.

For low fertility, the largest study showed heritability of 28% for women and just 4% for men. This is a low level of heritability; as an example comparison, 50 to 80% of IQ differences are thought to be heritable. Overall, this suggests that the majority of fertility issues are driven by circumstances outside of genetics.