If my brother has ocd, am I more likely to develop one?

Yes. The likelihood of others in a family getting ocd. Where one person has OCD is 3 to 5 times higher than that of a family where no one has ocd. Over a lifetime the chance of someone in the general public getting OCD is about 2 to 3 per cent. Learn as much as you can about OCD and if you think you may be developing the disorder, get the help you need to treat it. The earlier the better.
Yes, but not very. Obsessive compulsive disorder is an anxiety disorder. It's symptoms range widely in severity. It likely has genetic and environmental causes. Since genetic factors account for about 50% (+ or -15%) of OCD in children, you are more likely to develop it if your brother developed it as a child, less if he began as an adult. Also, 80% of cases begin in childhood, so you are unlikely to develop it now.