Grandmothers who smoked while they were pregnant are more likely to have grandchildren with asthma - even when mothers did not smoke during pregnancy, according to new research.
The fact that tobacco use affects genetic activity is widely known.
And the fact that parents' behavior before conception can influence gene expression is emerging: A man's weight at the time of conception can increase the likelihood of the child becoming overweight, suggests recent research, and what women eat just before conceiving can change a child's DNA for life.
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Now it appears that, on a genetic level, these behavioral influences can extend back another generation.
Children whose grandmothers smoked while pregnant with their mothers – even when their mothers did smoke while pregnant - were 10 to 22 percent more likely to have asthma. The data was gathered from nearly 45,000 grandmothers and over 65,000 grandchildren in Sweden.
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Rates of asthma have been soaring in recent decades, and this new information can also help asthma researchers better understand "risk from exposures in previous generations," study author Caroline Lodge said in a release.
The next step is to study the sins of the (grand)fathers, say the researchers: Would the same thing happen if a grandfather smoked at the time of conception?