However, science is now shining a new light on how dads affect their kids and grandkids. Through a process called epigenetics (‘epi’ means over or beyond genetics), environmental influences can alter which genes are turned on or off. Many of these alterations are temporary but some are not only permanent but can be passed on to future generations. That means dog dads may be contributing far more than simply their DNA to their puppies.

Scientists still know very little about how environmental forces transform sperm or how these changes get passed on through the generations. However, more and more research is showing that diet, age and life experiences can have profound influence on offspring. Here are just a few examples from research on other mammals.

A. Diet

• Human fathers that experience famine prior to puberty produce sons with lower rates of heart disease and greater longevity while fathers that have plenty during that time, produce sons with higher rates of diabetes.
• Human dads that start smoking very early in life, produce more obese children.
• Mouse fathers that are fed low-folate diets produce offspring with fertility problems and more birth defects.

B. Age

The bright spots are telomeres

• Older human fathers produce kids and grandkids with longer telomeres, which are linked to increased longevity.
• Older human fathers produce higher rates of autism and schizophrenia in their children.
• Older mouse fathers produce more offspring with behavioral and cognitive deficits.

C. Fears

• MouseMouse fathers that were cared for by stressed mothers have inappropriate stress reactions and pass these reactions on to at least three subsequent generations.
• Mouse fathers that are frightened in the presence of a unique odor produce kids and grandkids, even via artificial insemination (AI) so they never interact with the mother or the offspring, which have a fear-response to that odor and are generally more timid than fathers that aren’t frightened.
• Mouse fathers that are tormented by bully mice produce kids, even by AI, that are more timid and antisocial than non-bullied fathers.

It will be many years before epigenetics makes its way into the dog world. In the meantime, perhaps we should look at and care for our sires differently. Their life experiences, nutrition and age may be playing a major but previously unobserved role in our dogs’ health, lifespans, and temperaments. Many questions remain unanswered but all of these studies should push us to select healthy, stable, well-cared-for parents to produce the next generations of puppies; there is no place for timid, fearful, unhealthy dogs in the gene pool no matter how talented, beautiful or convenient they may be!

Selected Resources

Eisenberg, Dan, M. Geoffrey Hayes and CW Kuzawa. 2012. Delayed paternal age of reproduction in humans is associated with longer telomeres across two generations of descendants.  Proceedings of the National Academy of Science of the United States (PNAS), 2012.

Hughes, Virginia. 2014. Epigenetics: The sins of the father: The roots of inheritance may extend beyond the genome, but the mechanisms remain a puzzle. Nature 507, 22–24 (06 March 2014).

Hughes, Virginia. 2014. Sperm RNA carries marks of trauma: Stress alters the expression of small RNAs in male mice and leads to depressive behaviours in later generations. Nature 508,296–297 (17 April 2014).

Kaati G, Bygren LO, Edvinsson S.. 2002. Cardiovascular and diabetes mortality determined by nutrition during parents’ and grandparents’ slow growth period.  European Journal of Human Genetics,  Nov;10(11):682-8.