Kind of a dumb question about genetic heredity and protein.

[Quasirodent]

Ok so, my family believes that we are of a genetic lineage that has a mutation that makes it necessary for us to eat meat or take supplements for meat proteins because we can't produce them ourselves.
My mother tried to become vegetarian, and she got extremely sick after about 2 months, when her doctor also told her she had to eat meat for the same reason.

I've tried googling this, but I don't have a very good grip of the terminology, so I get a half million results to my query and I don't know how to narrow them down.

But I want to know if this is a real thing or if it's an urban legend that's just been accepted in the medical community (which happens more often than I like to think about.)

Edit: Looking into it further, I think it might be an inability to produce or metabolize specific amino acids that aren't found or are less plentiful in plant proteins.

[m52nickerson]

It more likely that your mom's doctor told her to eat some meat simply because she was lacking protein.  Your body pretty much breaks every thing down and than rebuilds what it needs out of those building blocks.  Vegetarians sometimes start of lack protein, and some of the nutrients that comes with protein.

[Cataclysm]

20 amino acids are necessary to make all your proteins. Meat has all of them. Vegetables don't, but if you eat a wide variety, you'll get it some from each. So maybe it's just that there are some vegetables your mom should have eaten but didn't.

[Osama bin Bambi]

I think that happens to basically anyone who doesn't eat enough protein in their diet. A lot of the vegetarians I know have to supplement their diets with supplements for precisely this reason because humans really evolved to be omnivorous.