Doctors have been telling men for years that smoking, drinking and recreational drugs can lower the quality of their sperm. And this affects the health of their unborn children.
Now, they have added other father qualities that can affect the composition of semen and may have an impact on a baby at the time it is conceived:
- how old are they
- what they eat
- the quality of the air they breathe
- their level of emotional stress
- their income and job situation
These findings are part of a new field of study called epigenetics. It means looking at things that make genes work the way they do. It means that genes are turned on and off by the way we live.
The impact can go on for several generations. Some scientists are saying that the rise in autism and schizophrenia is partly caused by older parents. They do not know for sure how it happens.