A study conducted at the University of Melbourne has determined that children are more likely to develop asthma if their father was exposed to secondhand smoke as a child. This risk increases even further if the father then went on to become a smoker himself.
This study was composed of 1700 children. Researchers looked at whether they had developed asthma before the age of seven. The data was then compared to whether or not their fathers grew up with parents who smoked before they were fifteen.
Researchers believe this could be a result of an epigenetic change, which is when factors in one's environment interact with their genes and modify the expression. These researchers believe that this could be passed down to the fathers offspring.
I would love to see more results from further studies of this topic, as they have a fairly small sample size. I am left wondering if this is truly the result of an epigenetic change, or if this is the result of people with smoking parents becoming smokers themselves.