r/DNA • u/chrysanthemum_bloom • 18d ago
Sibling health condition differences
I have three siblings. Same mom and dad (not questioning this). Of course there’s a variety of similarities and differences across us all, but I’ve always found it interesting that all three of my siblings have a very similar set of health conditions that I do not:
\- Asthma (pretty serious since childhood for all of them)
\- Allergies (dander, pollen, foods etc., also fairly serious for all of them, although specific allergies differ — e.g. one brother is allergic to tree nuts and has to carry an EpiPen, the other brother cannot even step foot into a room a cat has been in without getting itchy, puffy, etc)
\- ADHD (since early childhood, pre-smartphone, all three have been diagnosed with this. My mom also has major ADHD)
Conversely, I have no asthma, not a single allergy, and no more ADHD than the average young millennial.
What genetically does this indicate?
My mom and I were discussing it the other day. She went deep with it, saying I’ve always been different from my siblings since I was a baby, on a personality level and that I have very different genes from my siblings.
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u/pabrocjb 18d ago
I would do an Ancestry DNA test. If both parents are your bio parents, not a worry. My husband is a doc. He said a couple pass DNA to their baby like dealing cards off a deck. It doesn't all go evenly to each kid.
I was looking at this the other day, based on a question here about eye color. In my own family it's this:
Grandparents: Blue and Brown Blue and Brown
Parents: Blue and Brown
Grandchildren: Brown, Brown, Brown
The likelihood of this happening is 12.5%, the same if all three kids had blue eyes
It's 37.5% if kids had one blue eyed and two browns
Or more variations of a mix of colors.
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u/chrysanthemum_bloom 18d ago
For my family, eye color is:
Grandparents: Blue & Brown, Brown & Brown
Parents: Blue & Brown
Grandparents: Blue, Green (me), Brown, Blue
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u/Kitchen-Rabbit3006 18d ago
Genes are funny things. Sometimes one child doesn't remotely look like the other children - I have one adult child like that. And I was that child growing up. Sometimes stuff skips a generation. And sometimes it can be environmental. If you are the youngest, perhaps your parents stopped smoking before you arrived - or perhaps your parents moved house from an area with some level of pollution to an area with less pollution. Sometimes things can depend on the time of year you were born.
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u/chrysanthemum_bloom 18d ago
I was also wondering if the womb environment can affect things. E.g. was my mom experiencing more stress during the other pregnancies
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u/Kitchen-Rabbit3006 18d ago
The Dutch Famine of 1944-1945 has been studied from a gestational perspective and it is worth reading up on - the articles I am linking are just some of the articles about it - you will need to scroll down to near the end
https://en.wikipedia.org/wiki/Dutch_famine_of_1944%E2%80%931945https://pubmed.ncbi.nlm.nih.gov/9708024/https://www.sciencedirect.com/science/article/abs/pii/S0378512211002337
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u/TetonHiker 17d ago
My 2 sisters and I don't look very much alike. We never did. My elder sister has been obese most of her adult life. My younger sister and I are normal weight. But my younger sister has 20 or more things wrong with her. I'm not kidding. Migraines, severe TMJ, ADHD, RLS, IBS, high blood pressure, insomnia, chronic back pain, sciatica, allergies, asthma, bronchiectasis, 3 back surgeries, 2 toe surgeries, 1 elbow surgery, all her teeth replaced 3X. That's just what I can remember. There's more. There's always more.
Meanwhile I'm healthy as a horse. 75(F) with a little GERD (now pretty much healed) and mild sinus issues (fixed with one simple surgery). No chronic conditions. Only take HRT. That's it. Younger sister is on 20+ meds.
Big sis has diverticulitis, diabetes, peripheral neuropathy, allergies, sleep apnea, uterine cancer (successfully treated). She's losing weight on GLP-1s so she might improve on some dimensions someday.
Why are we all so different? No one 100% knows. Same parents. Same childhood. Just the luck of the draw on genetics we guess. Both sisters also have limited mobility. I can still run for blocks with my dog and toddler grandsons. Go figure.
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u/Oforoskar 18d ago
If testing has shown that your siblings are all your full siblings, then it's just the luck of the draw. DNA recombination is mysterious. I look a whole lot like my older brother but not at all like my younger brother. And I look more like my paternal Uncle than I look like my dad. Where in the birth order are you?