I think to some level (s)he's right, considering that some people are vegan because meat, fish and poultry grosses them out. I was like this as a kid and my dad tried to force the veganism out of me, he succeeded with delicatessen & poultry but I'm still physically revulsed by meat and fish, far worse than before.
On the other hand (and I'm gonna ask you to read until the end without losing your temper because this is controversial), I think everything in life is a choice, including who you are. You can control yourself and work against your nature if you think that's better (it's how you overcome fear for instance), and you can persuade your brain not to love people of the same sex. BUT! even if it is technically possible, it is still really hard, and more importantly unethical and unhealthy. And if you don't consider it an option in the beginning you have less chances of being gay. A "why not? less try" and you enjoy it so you stick with it. [c]

If you look at it from that angle, I think for SOME people being gay CAN be a choice, conscious or not.
So at the end I think there's a little fraction of vegans out there who didn't choose to be vegan and a little fraction of people who "chose" to be gay. From this point of view, veganism can be compared to gayness. But this is like 1% (no statisticians around?), and should not be generalized anyways.
I would like to know however if your friend meant it like that or not.

Your friend reminds me of people in a vegan group that I trolled (cause they always overreact and it's hilarious)
They talk about veganism as if it would fix every problem in the world
And meat eaters are all going to end up in hell

Mom, dad... I'm vegan

Some people have enzyme deficiencies, but really, your friend must be very ignorant.
@rosalinas They sound ridiculous. At least all vegans aren’t like that or we’d have a crazy problem.

Yes, they even say if we want to eat meat, we should go to the wood and hunt with our teeth and eat them raw like animals
Lot a of vegans are lovely

Why are some people so extreme these days. Who cares what you eat, most vegans are fine people, after all your choice in food doesn't change your personality. Those odd few who act like it's some divine way of life that'll save you annoy me to no end