New research has found a link between older fathers and higher rates of autism and schizophrenia in their children, upending the long-held belief that mothers were the primary contributor to a child's health.
But beyond this, researchers are finding that things like stress levels and obesity in even young fathers have an effect on their children and those effects may persist for multiple generations. So how much do our fathers - or even grandfathers - matter to our health?
"It's been very established and accepted in our society that the age of the mother or toxic exposures of the mother during pregnancy can affect the offspring," said Dolores Malaspina, a psychiatrist at New York University, on The Daily Circuit Thursday. "But society has had a hard time accepting the emerging data that the health of the father can influence his sperm and influence the health of the offspring. We think now the effect of father's age and health may even be greater than that of the mother."
Malaspina said problems arise in cells when they divide.
"We know that it's dividing cells that are most susceptible to radiation, or chemotherapy or toxicity," she said. "We just need to step back and realize men are always making more sperm. From puberty forward these cells are dividing and replicating and so they are susceptible to changing based on the environment."
Despite the new research, the probability of an older father producing children with autism or schizophrenia is still very low.
"The good news is that the vast proportion of children with older dads are perfectly fine," Malaspina said. "We also know that being wanted, a wanted pregnancy, carries a lot of protection to the child as well. It's just that the proportion of children with problems goes up as men age... I just want people to be aware early in their life when they plan these families to understand these risks."
Judith Schulevitz, science editor for The New Republic, wrote about the importance of fathers for The New York Times. She also joined the discussion on The Daily Circuit.
"I wish couples, both men and women, felt pressure to have children younger," she said. "But I don't really want it to fall on individual couples."
Schulevitz said there are a number of factors contributing to childbearing beginning later in life, including feminism, birth control and workforce constraints.
"There are things that social policy could do to make it easier for men and women to have children younger that aren't being done," she said. "I would like there to be a conversation on the national level."
On the blog, Elise Bender said this conversation reminded her of an earlier discussion on The Daily Circuit about women "having it all."
"I feel that currently we can't because our physical maturation, emotional maturation and education and job prep time are not in sync with the best time to have children," she wrote. "Plus societal norms are adding to the barriers. I am now in my mid-30s and wish I had more energy for my young children. Had we been able to start a family earlier maybe I would feel different. I feel fortunate to be able to stay at home during their critical years of development. I know this is a sacrifice that will have ramifications for my future employment. This choice does limit us. But I feel it is best for our children."
Does the male biological clock matter to you? Comment on the blog.
MPR News' Madelyn Mahon contributed to this report.