Q:

My parents are overweight, my father has high cholesterol and two of my grandparents had diabetes. How much good does it do to change my lifestyle if these problems run in my family?

A:

It’s true that many health problems do seem to affect generation after generation. But that doesn’t mean the condition is genetic–and it certainly doesn’t mean it’s inevitable. The fact is, we don’t give our children only DNA. We also give them recipes for living. We pass along tastes for certain foods and ways of eating that can have a major effect on health. Often, what appears to be a genetic trait is actually a set of food habits passed down. Here’s a look at some of the health conditions that commonly occur in families.

High cholesterol We often hear people say, “I have high cholesterol; it runs in my family,” assuming that the problem is out of their control. It’s true that some cases of high cholesterol–perhaps one in ten–really are genetic. The rest are caused by our food choices: Even small amounts of animal-based food products contain enough fat and cholesterol to push our own cholesterol levels up.

The only way to really know if the problem is genetic is to completely eliminate animal products from your diet while also keeping vegetable oils very low. Then, after about eight weeks, see your doctor. If your cholesterol is still too high, blame your genes. If you do have a genetic tendency toward high cholesterol, continuing with this same plant-based diet will minimize your risk.

Overweight There’s no question that genes play a major role in what we weigh. Genes even affect where the weight ends up, such as around our waists or on our hips. Some rare genetic disorders cause massive weight gain early in life too. But most weight problems have much more to do with our food habits than our genes. After all, the tremendous increase in obesity in recent decades has occurred while our genes have remained the same. And people who switch to a low-fat, plant-based diet lose, on average, about one pound per week without needing any sort of rearrangement in their genes.

We can draw an important lesson from Japan’s history with obesity. A rice-based diet kept obesity rates there under 3 percent until fast food outlets and other Western tastes invaded, causing the rates of weight gain to climb. But shifting away from a meaty, fatty diet can reverse this trend–both here and there.