Yes, OCD can be genetic, and different family members can have different forms of it, so you could have gotten it from your grandma (who probably got it from other family members) without having the same symptoms. Part of how OCD develops is influenced by your experiences in life, which are different from your grandma's.

I don't know anyone who has OCD in my family, although there are all kinds of mental problems. Same thing with panic disorder.

I think it's sad that your family talks about your grandma that way, but that's the way it is with most victims of mental illness. I don't know if it would be a good thing or not, but maybe you should consider contacting your grandma, and maybe seeing if she's gotten help, or even knows about modern help, and letting her know that you could use advice from what she's learned living with OCD. Perhaps you could find some support in your family that way, someone who knows what it's like.