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Researchers “Believe”

July 20, 2009

A study of 226 families by Plymouth’s Peninsula Medical School found obese mothers were 10 times more likely to have obese daughters.

For fathers and sons, there was a six-fold rise. But in both cases children of the opposite sex were not affected.

The researchers believe the link is behavioural rather than genetic.

(emph mine)

Wait, what?

Now look, I’m willing to acknowledge that I know next to nothing about genetics.  So it’s not like I’m saying I know they are wrong because I have any actual knowledge.  But when I see the words “researchers” or “scientists” and then see the word “believe” I become concerned.

Looking more closely at the actual release from the researchers we see the following:

The Study’s Director, Professor Terry Wilkin said:

“Any genetic link between obese parents and their children would be indiscriminate of gender. The clearly defined gender-assortative pattern which our research has uncovered is an exciting one because it points towards behavioural factors at work in childhood obesity.

“These findings could turn our thinking on childhood obesity dramatically on its head. Money and resources have focussed on children over the past decade in the belief that obese children become obese adults, and that prevention of obesity in children will solve the problem in adulthood. EarlyBird’s evidence supports the opposite hypothesis – that children are becoming obese due to the influence of their same-sex parents, and that we will need to focus on changing the behaviour of the adult if we want to combat obesity in the child.”

So, even here they have no real evidence for this claim beyond what their expectations would be.   They would expect obesity to be independant of gender, but it isn’t, therefore it is behavioral?  They seem to be missing a few steps there.

Here are at least four other ideas for further research here that don’t immediately jump to ye olde “fatties eat too much” theory.  I thought of them all by myself in approximately 5 minutes.  Now, perhaps they have already thought of and refuted all of these theories but it seems to me that if you did all that work you might have possibly mentioned it in your “Oh noes teh fatz0rz” rant.

1.  Hormones. This is such a duh explaination it kindof hurts.  If I have anything in common with my mom it is most definietly related to my “womanly cycles.”

2.  they are only looking at childhood obesity here, and comparing it to the current weight levels of adutls.  What if their thin parents were also obese in childhood?  (And what if people who were obese when they were younger are more likely to be married to someone who is actually obese than people who have been thin their whole lives?)

3. Additionally, dieting.  My mother, who is obese, encouraged me to diet from age 6.

4.   What about previous generations patterns of obesity?  Also, are they only looking at couples where both members are obese?  Or just one?

Edited to Add: 5.  It could be a sex linked gene (per everyone in the comments).  I stupidly assumed that if something like that were an option the genetics scientist would have mentioned it.  (I haven’t taken biology in over 10 years, so my genetics knowledge is pretty non-existent, thank you smart people for coming to my aid!)

I would really like to have a better understanding of their methodology here, but nothing pops up that I can use on google, which furthers my annoyance greatly.  I can’t tell if they were looking at only couples where both parents were obese, as they don’t mention that possiblity at all in the releases.

If anyone has any more information about this research, that’d be great.

Also, I’d be interested to hear how they refute this other study which is more robust.  It’s conclusions are clearly in opposition to their “beliefs” about what their research proves:

Stunkard ended up with 540 adults whose average age was 40. They had been adopted when they were very young – 55 percent had been adopted in the first month of life and 90 percent were adopted in the first year of life. His conclusions, published in The New England Journal of Medicine in 1986, were unequivocal. The adoptees were as fat as their biological parents, and how fat they were had no relation to how fat their adoptive parents were.

The scientists summarized it in their paper: “The two major findings of this study were that there was a clear relation between the body-mass index of biologic parents and the weight class of adoptees, suggesting that genetic influences are important determinants of body fatness; and that there was no relation between the body-mass index of adoptive parents and the weight class of adoptees, suggesting that childhood family environment alone has little or no effect.”

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16 Comments
  1. 5. It could be genetic, and sex-linked. In that case I would expect it to have a more striking correlation in men, because sex-linked things are so often Y-chromosome, but there are so many other factors at work, such as the higher prevalence of dieting among women.

  2. Mhorag permalink

    How about looking at the rest of the extended family – grandparents? Aunts? Uncles? Cousins?

    You can definitely tell everyone in my mother’s family is related (especially from behind). They all started out slim enough, but by the time they all hit 40-45, that’s when they start gaining weight, and all in the same places (hips, thighs, bellies – in that order, even the men).

    My maternal grandmother started out slim enough (98 lbs at 5’1″ on the day she married), but by the time she had her 6th child (she had a total of 13), she wasn’t 98 pounds any more. She weighed closer to 160, and this was when she washed over the washboard for 9 people, hung clothes out on the line to dry, scrubbed and waxed wooden floors, ironed sheets and others linens, did all her own canning and preserving, baked all her own bread and other baked goods, cooked everything from scratch, grew her own garden (vegetable and flower), walked everywhere she needed to go (yay, small town) etc. etc. She worked hard and physically and STILL put on weight from her pregnancies (all live births and all survived to adulthood, BTW). She got up at 4:30 AM every morning of her life and worked all day cooking, cleaning, and caring for her family. She was supposed on survive on celery sticks and lemon water and weight only 110 pounds?

    I was definitely born in the wrong century….

  3. Not to mention, for example, the possibility that one of the many genes that influence body size might be on the Y chromosome –and therefore passed from father to son?

  4. I wish I knew more about genetics so I could more confidently write an angry letter to this researcher. The claim he is making here is just so obviously false.

  5. Caitlin permalink

    Any genetic link between obese parents and their children would be indiscriminate of gender.

    Whee! Things that simply are not true for the win. Of course the parent you inherited a copy of a given gene from can influence how that gene variant affects you. It’s not common, but it ABSOLUTELY happens. (The most extreme examples are imprinting disorders like Angelman’s and Prader-Willi, but it also happens in the triplet repeat diseases, and in other cases. This kind of epigenetics is something we’re only starting to get a handle on and there is lilkely to be much more to discover about it, but anyone with any decent genetics knowledge would be aware of it.)

    Since this idiot doesn’t even know that, I rate the likelihood of his research being accurate or useful at about 1%.

  6. Caitlin permalink

    And I didn’t even consider that the genes might be on a sex chromosome, because it is so OBVIOUS I skipped over it.

  7. Caitlin permalink

    So obvious a possibility, I mean.

    Man, I am serial comment-y today.

  8. littlem permalink

    “But when I see the words “researchers” or “scientists” and then see the word “believe” I become concerned.”

    Bless you. You know? Because *not* reading in the sciences regularly, I am now flabbergasted to realize how often that sly little trick just rolls right by me — particularly on issues having to do with womens’ bodies — and now I will be able to read much more critically in the future.

    *blows you kiss*

  9. Caitlin, Whatigenetics? It does make sense to me that certain genes could be inherited only from a mother or father, but, I assumed (apparently wrongly) that the scientist studying genetics would have mentioned this if it was, y’know, an option. Apparently he’s just an idiot.

    Littlm *catches* I’ve been reading a lot of PZ Myers, I blame him. Seriously though, if a scientist is going to make a ridiculous claim they should at least be all “We think maybe this but we need to do more research.” This guy is just talking out his ass.

  10. Patsy Nevins permalink

    My mother was fat (& lived to be 85), my father was thin (& died at 63.) They had six children who survived to adulthood. One girl was slim in her teens, but getting fatter after the birth of her third child at 26 & likely would have become actually fat had she not had to have an emergency D & C, been overanesthetized, gone into a coma, & died 11 months later. Of the rest of us, the oldest son is built just like our father (& has always been able to eat three times what I do while castigating me for ‘letting myself go’). The other two boys are fat, the younger one bearing a stronge resemblance to our mother. The two other girls are fat. We have often lived far apart & had very different habits, lifestyle, tastes in food, but most of us, of BOTH genders are fat. And I am not actually built like my mother, but like her mother, who was also fat (& lived to be 90.) My three brothers are currently in their 70’s, the two fat ones whose weight has ranged between 250 & 270 for years as much so as the one thin one who thinks he is getting too heavy if he gets over 175. I have had many years of ample proof of the genetic nature of body size & shape, & plenty of research has indicated that it is even more heritable than height. These particular ‘researchers’ are, as are so many of them, talking out of their butts.

  11. Alexandra Lynch permalink

    So much can affect body shape. Every single woman in my blood family are heavy busted, slim-waisted with a belly after childbirth, and full-hipped and heavy-butted, with thick thighs. We are also tall, from 5’7″-6’3″. 90% get diagnosed in their thirties with thyroid issues. We all have the same loose ligaments in knees and elbows, too….which makes childbirth relatively easy on us, but means that if you take up running to keep your weight down, your knees go out of alignment. And the wide hips mean an increased Q angle, which also changes how the knee loads. And there’s a family ethic that one is never not doing something; sitting down means you’ve got knitting or sewing in your hands, and we multitask.

    But yet we all are over 200 pounds.

    The men tend to be tall big solid men, who develop a belly in their forties.

    Genetically, I think my sons will follow the tall pattern on both maternal and paternal sides; when they hit their late thirties, they may discover they must change their eating patterns. For now, both are growing into tall well-muscled fellows.

  12. Caitlin permalink

    shinobi, epigenetics is any heritable change in gene expression that isn’t due to a change in the actual base structure of DNA. In its classical sense it refers to alteration (DNA mathylation and histone acetylation/deacetylation usually) that’s passed on to the daughter cells when a cell divides. So you might have a copy of gene variant A, but if the DNA is methylated this copy is silenced and you won’t see the effect of it because no product is being made. If the cell in which a copy of gene variant A has been silenced in this way divides, both daughter cells may also have gene variant A silenced in them and may not show any gene variant A product either, EVEN THOUGH BOTH PARENT AND DAUGHTER CELLS HAVE FUNCTIONAL COPIES OF GENE VARIANT A.

    Nowadays it’s being used to discuss when this kind of alteration — patterns of DNA mathylation or histone acetylation/deacetylation — are passed from parents to children. So, say, your mother’s copy of gene variant B is methylated and you inherit that gene variant from her. If you inherit the methylation it may be that neither you nor your mother will ever produce the product of gene variant B EVEN THOUGH YOU BOTH HAVE FUNCTIONAL COPIES. In this way the parent you inherit each copy of gene variant B from would ABSOLUTELY have an effect on the phenotype (external characteristics) seen in you.

    For example, if the variant of gene B you inherit from your father acts in a pathway such that it predisposes you to store energy as fat more than the average person, and the variant you inherit from your mother acts in the opposite fashion and predisposes you to store it less, you have three possible scenarios:

    1) Both copies functional — you convert energy to fat at an average rate
    2) The copy you inherit from your father has a pattern of methylation — you convert energy to fat at a lower rate than average (because only the copy from your mother is functional)
    3) The copy you inherit from your mother has a pattern of methylation — you convert energy to fat at a higher rate than average (because only the copy from your father is functional).

    Obviously it’s never that simple, but that’s an idea of how it works. It’s all new, and exciting, and really not very well understood, and the much more likely answer in this case is that the researcher’s biases got in the way of the facts.

    But I suppose my point for this discussion is, between sex-linking and epigenetics you absolutely can’t say that there’s no possible genetic explanation for a parent/child gender bias. Let’s imagine a scenario where gene variant B interacts with gene product(s) from the X or Y chromosomes. Hey, in that case it would be affected by both the sex of the parents AND the sex of the children! Imagine that! No no, it must just be the baby doughnuts.

  13. Caitlin permalink

    *any heritable change in gene expression that isn’t due to a change in the actual base sequence of DNA, I should say

  14. JupiterPluvius permalink

    Yes, obviously male-pattern baldness is not genetic, because bald men are no more likely to have bald sons. You know what else isn’t genetic? Hemophilia, am I right? Because hemophiliacs don’t have hemophiliac fathers WAIT WHAT THAT’S NOT HOW GENETICS WORK YOU FAIL TERRY WILKINS

  15. Slim permalink

    I am having my mother’s cramps at this very moment.

    Also, “I’d be interested to hear how they refute this other study which is more robust.”

    By saying they don’t believe it?

  16. This is ridiculous. My mother was thin until her first pregnancy and never again. Now guess what? Exactly the same thing happened to me, too. We now look nearly identical. I thought it was obvious that I must have inherited a tendency to gain weight from pregnancy on, which OBVIOUSLY cannot happen to men … so why shouldn’t the same be possible at other stages of life? Hormones, anyone? I’m no expert and don’t know a thing about hormones in children, but I do know that the human metabolism is very complex and there is no need to jump to conclusions just because the real explanation hasn’t been found yet.

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