Geese are mean??

No, geese are not inherently mean and agreesive.  Unless it's mating season, or a goose has a nest of eggs she's brooding, or some goslings she's raising.

SOME breeds are more aggressive than others, Chinese for example.  Some Pekins can be aggressive.

I'm no expert, but I think the goose in those pictures is an Embden. 

I have a pair of (utility) Toulouse geese, a gander and a goose.  They're friendly and curious and such fun to have in the flock!  If somebody enters the yard, they will announce it with honking, and will run towards the person with their wings outstretched and flapping.  Pretty impressive display, but if that person were to wave HIS/HER arms and run at them, the geese would turn and go in another direction.

Well if you raise just one goose in your house and it thinks it is a human Im sure it has a different attitude then say my geese do as they grew up among their fellow geese and became attached to each other not me, they also live outside not in the house and I dont pick them up and pet them every day so I think those things play a part on weather or not the goose is tame and nice and you can try and buy a breed that is known to be easy going, the geese your mom was talking about sound like they could be Embden geese. The goose in the pics is most likely a Sebastopol Goose, look them up I hear they make great pets and are very pretty neat birds

I had a pair of Chinese I raised and they imprinted on me and I let them follow me everywhere. As the gander matured I nipped any aggression in the bud. He NEVER bites and never chases people. He's very nice and won't even bite when he's mad. He made a great dad too. I think that just like dogs it all depends on the owner training properly and making sure they know that aggression towards people is never ok. They were so smart they announced when cars other then our own came up and even understood when I introduced new chicks that they were not allowed to be mean to them, even the day old chicks where left alone. They also removed all predator problems including hawks and stray dogs.

Blue eyes, appears to have streamers, I vote Sebastopol goose and they are some of the calmest.

How they are raised has a large part to do with it, some geese are more aggressive just like some roosters can be.

If you brood your own, as in getting day olds and putting them under a heat lamp they will imprint on you and it's too late. They now think humans are the same species and will be agressive. Yes, some fear helps some. BUT in MHO I would rather have a goose that been handled a lot and knows to not be aggressive to humans EVER then to have a "wild" goose that just might attack.

I was 15 when I got them and had very young siblings so both geese and roosters were made very clear to that aggression to humans of any size was not allowed, especially biting. My Gander did hiss to protect setting girlfriend but he knew better then to try anything else

with you on the Chinese... all except predator protection.
I've had and still have them... they are not necessarily more agressive than other breeds but I think they're the loudest!  more likely to alert, and darn loud when they do!
over the years we've had a number of dog attacks and a couple of coyote raids, and for the most part they've survived the attacks better than any of the other birds (ducks chickens guineas turkeys), but the don't actively defend the other birds from predators.  good at alarm, not so much on defense.
I think the brown chinese are the most beautiful of the domestic geese, but not the best choice for a hand-raised pet.

My pair was a white chinese gander and a brown chinese goose. Mine did not directly protect the other birds as they didn't consider them "flock" but they defended my six acres as their property. I certainly can't speak for other geese but I witnessed mine chase off cats, coyotes, foxes, packs of stray dogs, and skunks. And they made such a racket about the hawks the hawks didn't stay lol

I agree looks like Sebastopol goose.  I have a Toulouse  that is down right mean.  She only likes me.  She was hand raised  and when she was young she was very sweet to every body.  But once she matured she turned very aggressive and no matter what we have tryed to get her under control she just doesn't want any body back out at the barns.  I don't need a watch dog I have her! She has good days and bad days.  She is just very moody! So even though I raised her to be a good and friendly goose it didn't turn out that way.  They are not all that way but  the Sebastopol are known to be very sweet.  I wish I had one.