Are Fathers and Mothers Equally Likely to Pass on Genetic Mutations?

Genetic mutations are alterations that appear randomly in our DNA, and we can receive new genetic mutations from our parents that have occurred in sperm and egg cells. All humans are born with around 60 new genetic mutations passed on from our parents, and while most of these anomalies have little to no affect on the way our bodies or brains function, some of these mutations are thought to be responsible for rare childhood diseases. The Icelandic genetics company deCODE wanted to gain a better idea of exactly where (or more accurately, who) these mutations are coming from, so they sequenced the genomes of 14,688 Icelanders. Their findings indicate that fathers pass on four times as many new genetic mutations to their offspring as mothers do. Older parents are also more likely to pass on mutations, especially older fathers. The researchers found that, on average, men pass on one genetic mutation for every eight months of age, while women pass on one mutation for every three years of age.

Older fathers, new problems:

• On average, a 30-year-old father would pass on 45 mutations, while a 40-year-old father would pass on 60 mutations. A 30-year-old mother and a 40-year-old mother would pass on roughly 10 and 13 mutations, respectively.
• Men pass on more mutations because they produce sperm throughout their entire lives, and because the DNA replication process is imperfect. Women pass on fewer mutations because they are born with all the eggs they will ever have.
• Previous research has shown that children born to older fathers have a greater risk of developing disorders such as autism, schizophrenia, and intellectual disabilities. Scientists say new mutations may be the cause.