animal protein is a large part of maintaining & growing healthy musculature, which is a generally a male pursuit.
The girls I know who left vet school or biology school upon hearing they’d have to disect worms didn’t get to see the blood. My high school class had both a guy and a girl faint at the sight of blood; several girls were all yucked out by the notion of “go get some worms from the garden, we’re going to kill and cut 'em” and had no qualms about complaining - there may have been yucked-out guys but they didn’t make any noises.
Mind you: a lot of my generation had not entered the kitchen except to beg food, prior to going to college. Your sister’s classmates evidently got a better education from their mothers, good for them!
That’s an anecdote though, not a stereotype.
When I say the stereotype is not to care about animal welfare, I don’t mean that men are supposed to be cruel, merely that it’s not seen as the masculine thing to be empathetic.
Our level of care is supposed to be limited to “Kill it quickly” not “Don’t kill it at all, if there’s an alternative”, let alone “Don’t keep animals in battery (factory) farms, it’s cruel”.
My cite is the episode of the simpsons where homer tries to make bart into a real man (and prevent him becoming homosexual) by taking him out hunting. I’m not saying the stereotype is true or makes sense. Merely what the stereotype is.
See, as a veterinarian, I heard that never from my fellow vet students (mostly females), but I did indeed heard that beforehand. Female teens, girls who say that about veterinary medicine. But it is just a dream, like boys saying they want to be a construction worker or policeman (and ending in a different career altogether).
Most of those that reach vet school already know it is all not “cute and fluffy”. Heck, we used to joke and roll our eyes at guys who would say that to us thinking they were being smooth.
To recap: Little girls and young females exclaiming that idea, yes, I’ve heard. Adult women, intent on becoming veterinarians, and already in vet school? Nope. And even if one faints, so what? I fainted the first time I volunteered, I now dissect those animals and do necropsies with little problem (horrid decomposing smells are hard to ignore).
PS. I wonder if the difference has to be, in part, that in the US, veterinary students are older in general than in other countries (and subject to different requirements). Hence, the weeding of the softies has been done before. An 18 year old teenager with no previous animal experience is different from a 21 or older adult that has had to gone through several volunteer rotations that include undesirable tasks.
And still, in the US, female veterinarians are on the rise.
We vegans tend to be good cookers ourselves. 
** Meat! Meat Good!**
That’s about it.
Some of this is beyond GQ, but . . . women like being “special.” Some women like having their demands catered to. Having very narrow dietary “requirements” isn’t a bad start to either . . . .
As a non-vegan I would love to be presented with a box of steaks.
Not sure how relevant this is, but being vegan is fairly difficult unless you’re a capable, comfortable cook. It’s much harder to rely on outside sources, both due to price and scarcity.
Females tend to be taught how to cook more. So it’s a little more viable.
Not sure how much that impacts the stats, but I have to imagine it’s a factor.
Mainly, since America is an intensely other-directed society masculinity there is not internal but depends upon society’s judgement ( and more particularly that of local community ).
I know of some American males who detest or are wholly indifferent to sports, but feel impelled to feign interest in order to get along and not be judged inadequate. Same with an interest in cars and sometimes weapons/hunting. Male America is still paranoid, as noticed back in the 1940s by sociologists, about being considered ‘sissy’. ( Which accounts for much of it’s interesting military adventurism and a love of military patriotism that would have been considered weird to 19th century Prussia, but well-admired in Sparta. ) To express concern for animal welfare or willingness not to exploit indicates to those around one is in the same camp as PETA and is unfriendly and self-centred to the group.
In any case, vegetarianism, let alone veganism, is suspect in the USA — which always takes suspicion to extremes when it considers anti-conformity, whether it was commies in the 50s’ or anti-gay rights people now — and the population proportion of either is very small compared with other western countries. It’s something like 2-4% vegetarian against 9-10% in Britain or 10-12% in Germany.*
- Naturally, latin countries normally have far fewer vegetarians, and as the USA becomes more hispanicized Catholic church attendance should increase, along with more conservative social mores, but this won’t add much to the proportion of vegetarians.
From my childhood in the 1960s, I remember Jungle Larry, whose motto was “Bring 'em back alive!” (I.e., capture wild animals, don’t kill them.) He used a he-man adventurer public image to promote conservation of wildlife.