Are these things inherited or do you just get them?

[Mummystootired]

I'm just wondering about some health issues that are in my family,(aunts and uncles) whether these are things you get genetically or some people just get them and others don't if you see what I mean.
Arthritis,
Manic depression,
Memory problems

Bipolar disorder runs in families. I think I read that if you have a close relative with it, you have a 1in 10 chance of developing it, but dont quote me on that. Dont know about the others.

I would suspect you get both. ie there are some that are genetic, some that are brought on by an illness/stress/enviroment.
I would guess that certainly for the depression (possible others too) it would be genetically disposed, rather than a certainty, so a mixture of genetically likely to get it if something sets it off.

genetic susceptibility definitely, however environment/diet/nutrition also contribute to them

Thanks for replies everyone