Smoking May Be a Risk Factor for Schizophrenia

[fasttense]

4. Or is it that those with the TCF4 gene variants who process acoustic stimuli

in a deficient way and are more likely to smoke?

It reminds me of the bra scare. About 10 or 20 years ago, health scientists were going around saying that bras caused cancer because bra wearing women were more likely to get breast cancer. Women who wore bras the most were the most likely to get cancer. But it turned out women with larger breasts were more likely to wear bras AND were more likely to get breast cancer (because the bigger they are the more there is to get cancer - same reason men are less likely to get breast cancer.) Cause and effect are not always evident in statistical studies and I doubt it in this one too.