Men could end up with penises half-an-inch shorter than usual if their parents were exposed to high levels of a chemical used in non-stick frying pans.
Scientists have found the chemicals, called PFCs, can interfere with male hormones and lead to sexual organs being 'significantly' shorter and thinner.
And this effect is not only seen in the womb, the researchers said. PFCs could have toxic effects in teenagers, too.
The chemicals, also found in waterproof clothing and greaseproof packaging for food, get into the bloodstream and reduce testosterone levels.