When it comes to weight problems, many people, including experts, are inclined to put much of the blame on genetic predispositions.

Yes, diet and lack of exercise are also known culprits, but ultimately our genes determine how well or badly we fare, common wisdom goes.

Now a new study claims that those we share our lives with, our spouses and partners, have a much greater influence on our health- and fitness status, regardless how genetically programmed we are.

The more decisive factors, it seems, are the choices we make in connection with other adults. Even the diet and lifestyle patterns established during childhood and adolescence eventually cease to dominate, according to the researchers.

“By middle age, choices made by couples – including those linked to diet and exercise – have a much greater impact than the lifestyle each shared with siblings and parents growing up,” they say.

The good news coming from these findings is that people who are obese and suffer from related illnesses are not cursed by birth or poor upbringing but can make changes that supersede their genetic profile. Even those who come from families with a history of weight issues can lower their health risks by altering eating and lifestyle habits, says Dr. Chris Haley, a professor of the Medical Research Council’s Human Genetics Unit at the University of Edinburgh and lead author of the study report.

Husbands and wives can be each other’s role model for both healthy and unhealthy behavior, says Miranda Hitti, a medical writer at WebMD. They can function as a mutual inspiration for positive changes like improving their diets, taking up exercise routines, giving up smoking, getting regular physical checkups, and so on.

Unfortunately, loved ones can also get in the way when corrections are needed. I have seen it happening in my own practice as a dietitian and health counselor time and again. One party is ready, but the other isn’t and refuses to join in. Now there is a conflict, and oftentimes the one who wants to change course loses out and gives up.

There can be multiple reasons for noncooperation between life partners, including emotional misgivings like insecurity and jealousy. To overcome these kinds of obstacles, skillful communication is crucial.

If you have a significant other who is out of shape but not interested in doing anything about it, you can’t force them into making better choices. Nagging will not work. If it’s not his or her own idea, there will likely be a lot of resistance and rejection. But what you can do, is trying to plant a seed and getting the conversation started, by being supportive and building your case on positive rather than negative emotions, advises Steve Kamb, the founder of NerdFitness.

Without support it can be extremely hard to accomplish goals like weight loss and other health-promoting measures in any environment. But encouragement motivated by love, respect and concern for each other’s well-being is the best starting point any of us can hope for.

Timi Gustafson R.D. is a registered dietitian, newspaper columnist, blogger and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun”®, which is available on her blog and at amazon.com.  For more articles on nutrition, health and lifestyle, visit her blog, “Food and Health with Timi Gustafson R.D.” (www.timigustafson.com). You can follow Timi on Twitter, on Facebook, and Google+.